( CNN) Belief it or not, Oprah Winfrey get nervous.

“I didn’t want to take on this role, ” Winfrey told CNN at New York premiere of her new HBO film “The Immortal Life of Henrietta Lacks.” “I was intimidated by it. I was nervous. I simply didn’t know if I could do it.”

Based on a 2010 best-selling volume, “Henrietta Lacks” tells the story of a woman being treated for cancer, whose cells were taken without permission in 1951 and used in research for decades — unbeknownst to her family. Winfrey stars as Henrietta’s daughter Deborah Lacks.