Ruffalo, 48, who is an executive producer on the film, addressed the backlash over the "White Collar" star's involvement in the film on Twitter.
"To the Trans community. I hear you. It's wrenching to see you in this pain. I am glad we are having this conversation. It's time," he tweeted.
In another post he wrote, "In all honesty I suggested Matt for the role after the profound experience I had with him while making The Normal Heart."
When some called for the 38-year-old star's role to be recast, Ruffalo responded that the film had already finished its shooting.
"The movie is already shot and Matt poured his heard and soul into this part. Please have a little compassion. We are all learning," he tweeted.
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