On Wednesday, Upton -- who was the face of Guess in 2010 and 2011, and appeared in multiple campaigns -- tweeted, "It’s disappointing that such an iconic women’s brand @GUESS is still empowering Paul Marciano as their creative director. #metoo."
"He shouldn’t be allowed to use his power in the industry to sexually and emotionally harass women #metoo," she later added in the Instagram caption of a screenshot of her tweet.
"My position on these issues is well known, as I have been very vocal about them," the statement reads. "I do not condone any acts of sexual harassment, violation, or misconduct. Any accusations should be fully and thoroughly investigated. I will continue to support our rights as women.”
Upton did not elaborate with details about her complaint on social media. Meanwhile, TMZ reports that 65-year-old Marciano says he's "shocked" by Upton's accusations of sexual harassment, and won't apologize because "he's done nothing wrong." He also insists he's never touched Upton, or was ever alone with her.
"If she has a claim, there's one place to tell the truth and that’s in court or to the police," he tells TMZ.
ET has reached out to representatives of Upton and Guess for comment.
On Wednesday night, Lopez and her boyfriend, Alex Rodriguez, attended the launch of her Guess Spring 2018 campaign in Los Angeles. Lopez pulled out all of the stops for the event, sporting a skintight baby blue dress and a matching fur coat. The superstar left her hair curly for her glam night out.