Judd Apatow, Rita Wilson Show Support For Kesha After Her Removal From Billboard Music Awards Line-Up

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She may not be able to perform, but Kesha has a lot of supporters in her corner.

The True Colors singer will not perform at Sunday's Billboard Music Awards -- which air May 22 on ABC -- after she and the awards show say Dr. Luke's record label, Kemosabe Records, rescinded their approval for her to appear. Dr. Luke has not commented on the matter.

After hearing the news, many expressed their outrage, including director Judd Apatow, who tweeted, "Dr Luke can prevent Kesha from even performing?!! What kind of contract gives him that kind of power? F**ked up."

WATCH: Kesha Says She 'Won't Be Allowed' to Perform at Billboard Music Awards

Rita Wilson also spoke out, writing, "Doesn't this seem wrong on many levels? Kesha has every right to perform. Chris Brown was able to perform after his troubles #KeshaforBBMas."

Kesha's mother Pebe Sebert has also sent out many tweets regarding Kesha's blocked performance.

WATCH: Kesha Sobs as Judge Denies Request to End Her Contract With Dr. Luke and Sony Music

"So are Keshas constitutional rights being violated now, judge Lady?Does every adult woman need a mans permission to do what she loves?" she wrote. "Does Kesha have the right to pursue her happiness? Or did they only mean that for rich men?"

"Do you think that there is one male singer who could ever be 'not allowed to sing' on the Billboard Awards by another man???" she continued. "How much more public abuse does my daughter have to take before someone says 'Enough is enough'!"

WATCH: Kesha vs. Dr. Luke: Everything You Need to Know About the Ongoing Legal Drama

See the rest of her tweets below.

MORE: Kesha Says She Was ‘Offered Freedom’ If She Lied About Her Rape: ‘I Will Not Take Back the Truth’

Sebert went on to call for other artists to boycott the show, writing, "Wouldn't it be nice if other artists stood with Kesha and refused to preform if she is not allowed to sing!"

Meanwhile, the #FreeKesha movement is attempting to organize their own boycott of the show.

A representative for the movement told ET, "The #FreeKesha group is planning to boycott the BBMAs unless Kesha is allowed to perform. In addition, we are conducting a Twitterstorm in which we're asking celebrities who are attending (hosts Ciara and Ludacris, as well as presenter Ashton Kutcher and performers Adele, Meghan Trainor, Rihanna, Demi Lovato, Ariana Grande, etc.) to speak out in support of Kesha during the show."

Yesterday, a source told ET that while Kesha was previously approved for the BBMAs performance by the label, once Dr. Luke saw reports that Kesha was planning to slam him in the show, the approval was rescinded.

MORE: Kesha's Sexual Assault Case Against Dr. Luke Put on Hold One Day After She Vows to 'Take Her Life Back'

"Kesha provided Dr. Luke with written assurances that she would not talk about him, mention him or even allude to him in her performance, but as of now Dr Luke still has not approved it," the source added. "Dr. Luke could eventually change his mind about this, however Billboard has a spot to fill for the award show and they've got 5 days to do it so if a resolution isn't reached soon it's likely there's nothing that can be done."

"Myself and other Kesha supporters are boycotting the Billboard Music Awards unless Dr. Luke allows her to perform," said the #FreeKesha movement's Michael Eisele. "It's absolutely ridiculous that he continues to ignore the public outcry over his denial of Kesha's creative freedom. Myself and the 230,000 people who have signed the Care2 petition to free her will continue to fight back against his cruel and sexist suppression."

Kesha wrote on Instagram that she had planned to perform Bob Dylan's "It Ain't Me, Babe" at the show, adding that the performance, "has never had anything at all to do with Dr. Luke."

The controversy arises after Kesha's sexual assault case against Dr. Luke (real name Lukasz Gottwald) was put on hold while the singer resolves her breach of contract lawsuit in New York. Kesha alleges Dr. Luke drugged and raped her in the suit, and the producer has dismissed those claims as "outright lies."

Watch the video below.