Stars Grieve on Twitter for Alice in Chains' Mike Starr

Dr. Drew, Dane Cook, Nikki Sixx, Chris Jericho and two of Starr's "Celebrity Rehab" castmates are among those weighing in about the band’s co-founder, who was found dead Tuesday.

Dr. Drew Pinsky and other celebrities took to Twitter to express their thoughts about the death of former Alice in Chains bassist Mike Starr.

Starr, who has publicly struggled with drug addiction, was treated by Pinsky last year on VH1's Celebrity Rehab andSober House. The 44-year-old was found dead in a house in Salt Lake City on Tuesday.
"Devastating to hear of Mike Starr succumbing to his illness," Pinsky wrote. "So very sad. Our prayers are with his family."
His Celebrity Rehab castmate Mackenzie Phillips took some grief on Twitter over her tweet: "Mike Starr was a great and troubled guy. I loved him. He would be so happy to know he's a #TT right now. Rest in Peace, brother. #dopekills" (#TT refers to "trending topic.")
After sending the tweet, she received some negative responses from other Twitter users.
"@MackPhillips  Do you really think Mike Starr would care that he's a trending topic? Way to trivialize his death," wrote T.J. McBride.
Brian Patrick asked: "@MackPhillips  Considering why he's a #TT, would he really be all that excited?" Philips responded that "you've have had to know Mike. He had a very dark sense of humor."
To another user, dubbed Jordan393 -- whose account now says "this user does not exist" -- Phillips wrote: "@Jordan393 I [wasn't] trying to be funny. I'm sitting here crying. Go f--- yourself, okay? Oh, and Mike would agree with me."
Meanwhile, America's Next Top Model's Lisa D'Amato, who also appeared on Celebrity Rehab with Starr, tweeted: "My stomach is in my throat. We love U, Mike. #RIPMikey."

She later added: "Mike Starr was my homey. He had a larger than life heart. My last visit w/him was a funny & sweet one. I'll always rmbr that. <3 #RIPMike."

Jennifer Gimenez, who appeared on Sober House as the house manager, also weighed in: "I'm SHOCKED and SADDENED for the loss of MIKE STARR."

A slew of rockers also tweeted their thoughts, including former Guns N' Roses drummer Steven Adler, Velvet Revolver drummer Matt Sorum, Motley Crue bassist Nikki Sixx, Lamb of God guitarist Mark Morton and former Dream Theater drummer Mike Portnoy.

Wrote Adler, a fellow Celebrity Rehab alum from a different season: "R.I.P. Mike Starr!! Such a sad day! :( :("

Sorum took the opportunity to send an anti-drug message: "Drugs and alcohol aren't a joke. Please take care of yourself and respect yourself. We lost Mike Starr today. Rest in Peace man."

Portnoy echoed the sentiment: "RIP Mike Starr... I watched his struggle on Celebrity Rehab and had my fingers crossed for his recovery... this disease kills... sad stuff..."

Sixx, who has struggled with heroin addiction tweeted: "RIP Mike Starr. Another fallen Soldier to addiction... :("

Tweeted Morton: "Horrible news. RIP Mike Starr."

Also among the celebrities sharing their thoughts via Twitter were comedian Dane Cook and pro wrestler/Dancing With the Stars contestant Chris Jericho.

"Mike Starr may you RIP," Cook tweeted. "Your music loves on forever."

Jericho also took an anti-drug stance and referenced Charlie Sheen and the actor's recent hoopla.

"Sorry to hear about Mike Starr's death," he wrote. "Amid all of the joking about tiger blood and winning, let's not forget that drugs kill people."