When Kendrick Perkins emerged as a key member of the Boston Celtics team that won the 2008 NBA championship, he credited his growth to Doc Rivers, the coach he called his "father figure.''

That is, until his "father" shipped him to Oklahoma City in 2011.

"Yeah, I didn't like that,'' Perkins told ESPN this week, chuckling at the memory. "I never wanted to leave those guys. Me and Doc didn't talk for a while after that.''

Real families tend to stick together through thick and thin, illness and injury, triumphs and disappointments. NBA "families" generally don't exhibit that same resiliency; once the foundation starts to crack, everyone starts to go their own separate ways.

Yet, a small, tight-knit group from that 2008 Celtics team has kept the title connection alive. Twelve years after Boston captured banner No. 17, there remains a regular group-text chain of basketball banter (and other choice topics) between Kevin Garnett, Paul Pierce, Rajon Rondo, Tony Allen, Doc Rivers, and yes, Kendrick Perkins.

(For those feeling nostalgic, ESPN will re-air two games from the Celtics' triumphant championship run Wednesday, with Game 4 of the 2008 Finals at 7 p.m. and the deciding Game 6 at 9:30 p.m.).

The text chain has survived trades, free-agent signings, reunions gone sour and reunions that never materialized. Consider that at the start of the 2014-15 season, the participants on the chain represented six NBA clubs: Washington (Pierce), Brooklyn (Garnett), Memphis (Allen), Boston (Rondo), Oklahoma City (Perkins) and the Los Angeles Clippers (Rivers). Through the years, the chain has endured hurt feelings and periods of silence between individuals who had beef with one another. But, as Pierce said recently, "There hasn't been a grudge between any of us worth holding onto.''

"The guys won't allow it,'' Perkins added.

"It's the closest group I've ever been around,'' Rivers declared. "It's amazing how often we all still reach out when something great happens or even when things don't go very well.

"There was a real family element to that group that I'll always cherish. It was very special, how protective they were of each other. It's what every coach would want to have for their team.''

The text chain can be as simple as checking in about family members and milestones for each other's kids, or as detailed as potential business opportunities to be considered. The most active texters are the retired players -- Garnett, Pierce, Perkins and Allen -- who regularly trade insults, and often get together in person in Los Angeles, where each of them has a home except Perkins, though he is regularly in town for his television duties. Garnett talks the most trash; when Perkins retired, he teased his friend on the chain, "What you doing now? Cooking at home wearing an apron?"

Rondo, now of the Los Angeles Lakers, is a spotty participant, but finds time to weigh in once a month, often with a simple query: "Everyone OK?" Rivers admittedly is "in and out" during the season as he tries to lead the Clippers to a championship, but he delights in reading the comments of his former players before bed.

Naturally, there have been some bumps in the road. When Boston dealt Perkins and Nate Robinson to the Oklahoma City Thunder for Jeff Green, Nenad Krstic and a future first-round pick in February 2011, Perkins and his teammates were shocked and disappointed. That transaction ultimately led to the origin of the chain.

Ten months after the deal, on Christmas Day, Rivers sent out the first text with a simple message: "Merry Christmas.'' He and Perkins hadn't talked much, but by then, Perkins had received a new deal from the Thunder and was enjoying his new home. Rivers' text ignited a flurry of well-wishes and conversation topics among the players, who, with the exception of Perkins, were still wearing Celtics green.

"It was nice to hear from Doc,'' Perkins said. "And by reaching out like that, it just got everybody talking all sorts of noise. As usual, KG was the loudest. He said to me on that first text chain, 'Don't you start getting too comfortable in Oklahoma, Perk. You know where your real family is.'''

It was Rivers, according to Perkins, who "basically raised me.'' Rivers urged his center to find a way to stand out in his role as a complementary player. He also didn't hesitate to confront a young Perkins when he let his nightlife interfere with his basketball responsibilities. "He'd come up to me and say, 'Perk, you need to get your rest,''' Perkins recalled. "He said, 'I know where you were last night. You were out partying, and you were sluggish in practice today. Do you want a long career or a short career? Because if you keep doing what you did last night, it's going to be really short.'''

Perkins was the first to depart Boston, but not the last. Allen left the Celtics as a free agent in the summer of 2010 after Boston made its defensive stalwart an underwhelming offer. He inked a three-year, $9.45 million contract with the Memphis Grizzlies and became the centerpiece of their defense. Boston felt his absence, because, as Pierce explained, "When he left, the heart of our defense went with him.''

Allen's impact on that 2008 championship team, both personally and professionally, became much clearer in hindsight.

"His love for the guys, his affection for them, and his loyalty really stand out," Rivers said. "He was really hurt over the offer we made to him in free agency. I don't think he wanted to ever leave.

"But, one by one, we all did.''

In the summer of 2013, president of basketball operations Danny Ainge, determined not to hold onto his aging stars the way the legendary Red Auerbach had with Larry Bird, Kevin McHale and Robert Parish, agreed to deal Pierce and Garnett as the centerpieces of a blockbuster trade with Brooklyn that netted the Celtics a treasure trove of first-round picks. That same offseason, Rivers signed a three-year deal to become coach of the Clippers.

One year earlier, sharpshooting All-Star Ray Allen, upset that Boston had entertained trade offers for him while he was sacrificing both minutes and shots, left the team in free agency to sign with the rival Miami Heat. It was a move publicly condemned by Garnett, Rondo and Pierce, although The Truth has since considerably softened his stance. It created a schism that, eight years later, Rivers is still trying to repair.

"The best part of that group, and, I guess, the worst part, too, was they're just so competitive,'' Rivers said. "They felt very strongly, 'You cannot leave this family. If you do, you're an outcast. And, if you go to a rival, holy crap, you're an extreme outcast.' So that's what happened with Ray.

"And, as the years went on, and we were all moving around in the NBA, those rules were still in play. If you made a move that affected the group, you had some explaining to do.''

Perkins said Rivers was particularly upset with him in 2015, when he also chose to join a LeBron James team, the Cleveland Cavaliers, instead of reuniting with him with the Clippers. The group text raised questions about choosing James over their championship coach. Perkins sat out the discussion, and there was sparse communication between him and Rivers for a while.

"I think Doc was mad about it,'' Perkins said. "One day, I reached out and told him, 'It wasn't that I didn't want to play for you. I was just trying to pick the best situation to end my career.' Then I reminded him, 'I didn't hold my hard feelings when you traded me.'''

"Perk probably did the right thing, but at the time I was hoping he'd come with us,'' Rivers said. "And the other guys had their own thoughts about it. You almost had to ask permission to make a move like that. Everybody weighed in.''

At the end of Pierce's career, he reunited with Rivers on the Clippers, aiming to be a valued elder statesman. But in his two seasons in Los Angeles, from 2015-17, Pierce averaged under 15 minutes per game and he was crestfallen over his reduced role. "It just wasn't how I thought I'd end my career,'' he said.

Time has healed most wounds among these key members of the '08 team, with perhaps the most remarkable reclamation between Rivers and Rondo. By the time Rivers left Boston, he and the point guard were regularly butting heads, and the need for some space in their relationship was evident.

"It's a great example of how a player can be one of your favorites and your least favorites at the same time,'' Rivers said. "We always had respect for one another, but Rondo drove me crazy sometimes.''

Rivers said the group text enabled the two to see each other through the lenses of the people who knew them best, and to rekindle their relationship. Even though he's still the coach of the Clippers and Rondo now plays for the crosstown Lakers, Rivers said he probably texts Rondo more than any of his ex-players.

"He texted me on Christmas Day this year,'' Rivers said. "I was going back and forth with him. I was laughing, telling him, 'It's great to hear from you, especially since we're going to be trying to bash each other's heads in about two hours from now.'''

Rivers said Rondo's texts include questions on how to guard certain sets from mutual opponents. He said Clippers assistant (and '08 Celtics alum) Sam Cassell recently jumped on to inform Rondo, "We're going to give you a bunch of bad information.'' Rondo retorted, "Go ahead and try. I'm too smart for that.''

Perkins said the group texted one another as recently as 10 days ago, discussing potential restaurant and podcast ventures. Garnett, he said, has made some savvy investments in the past year and has become their unofficial adviser on such matters.

All but Rondo have long retired. They are in a second phase of their basketball lives, able to sit back and reminisce about the glory days.

By text, of course.

"That's how we've stayed connected,'' Perkins said, "to the best part of our brotherhood that never died.''