Shortly after the Grey’s Anatomy star spoke out following Union’s recent and controversial departure from the NBC reality competition series after only one season, the Will & Grace star criticized the network in a group of scathing tweets.
“Thank you for this @EllenPompeo,” Messing, 51, wrote. “This is disgusting behavior from a network that has been my professional home for decades. Yes, women become ‘difficult,’ when their insistence on a respectful and professional working environment, is ignored.”
“Addressing a hostile work environment is inconvenient when there is a huge money making machine that is involved. It is cowardice, greed, and protection of the status quo revealed. Being ‘hands off,’ is inexcusable and reflects a laissez faire attitude toward systemic racism and sexism,” she continued, tagging Union.
NBC did not immediately respond to PEOPLE’s request for comment regarding Messing’s tweets.
Messing has worked on numerous NBC shows over the years. In addition to her role in Will & Grace from 1998-2006 as well as its revival — which will end in 2020 — she also starred in The Mysteries of Laura from 2014-2016 as well as Smash (2012-2013).
In her own tweets, Pompeo praised Union’s “commitment to speaking up to injustice.”
“It’s unfortunate that @nbc the same network that protected disgusting men like Matt Lauer and punished women for speaking out or not putting up with it…has not changed their practices or culture,” she wrote, noting the former Today show anchor’s firing for allegations of sexual misconduct. “Workplace cultures will continue to be toxic until there is unity and solidarity among all women. If you go for self in these moments you undermine the work we are out here trying to do. Obviously this network feels like they can operate like this and it’s okay.”
Pompeo went on to acknowledge that there have been issues on her own show at rival network ABC.
“Also I feel important to mention our problems on the Greys set and every set has them…some kind of issue …there’s lots of people in a workplace.. point is… exec producers and the NETWORK @abc cared enough to help us make change support is crucial,” she tweeted, concluding by saying that this Thanksgiving, she felt “thankful for all the women out there who refuse to put up with bulls—. 💯 💯 💯 ❤️💋.”
News broke last week that Union and Julianne Hough — who both joined the season 14 AGT judging panel back in February, taking spots vacated by Mel B and Heidi Klum — would not be returning for the show’s 15th season.
On Monday, blog Love B Scott reported that Union had allegedly spoken out about “problematic” situations on set before her departure. A day later, a Variety report made further allegations, with multiple sources telling the publication that while working on the show, Union had expressed concerns over racially insensitive situations during her time as a judge, including a joke guest judge Jay Leno allegedly made that was later edited out of the episode.
She and Hough, 31, were also both subject to “excessive notes” on their physical appearance, sources alleged in Variety‘s report.
A spokesperson for NBC and production company Fremantle responded to such claims with a statement on Tuesday to PEOPLE, saying: “America’s Got Talent has a long history of inclusivity and diversity in both our talent and the acts championed by the show. The judging and host line-up has been regularly refreshed over the years and that is one of the reasons for AGT’s enduring popularity. NBC and the producers take any issues on set seriously.”
In a statement to Variety, dancer/actress Hough denied that she had a negative experience working on the show.
“I had a wonderful time on America’s Got Talent, I loved working with the cast, crew, and producers. I am happy to continue my working relationship with NBC,” said Hough, who is set to star in two upcoming NBC Christmas specials. “I’m looking forward to what the future holds.”
Representatives for Hough, Union, Leno, and Simon Cowell‘s Syco Entertainment, which produces AGT, have not responded to PEOPLE’s requests for comment.
On Wednesday, Union broke her silence, sending a message to her Twitter followers and thanking them for their support during this difficult time.
“So many tears, so much gratitude,” she tweeted. “THANK YOU! Just when you feel lost, adrift, alone… you got me up off the ground. Humbled and thankful, forever.”
Union also seemingly referenced the ordeal on her Instagram Stories earlier in the day with a video of herself working out alongside husband Dwyane Wade, who publicly supported her in a series of tweets earlier in the day.
“When the world feels like it’s falling apart. Try to find your peace,” she captioned the clip.