The Bridesmaids star has signed on to portray real-life science writer Rebecca Skloot in the film, which will be based on the author's book of the same name.

The movie will centre on the true story of Henrietta Lacks, an African-American woman whose cancerous cells were used in medical research to create the first immortal human cell line. It will be told from the viewpoint of Lacks' daughter, Deborah, who sets out on a journey to learn about the mother she never knew and how the unauthorised harvesting of her cells in 1951 helped change the medical industry.

"She was a poor black tobacco farmer whose cells - taken without her knowledge in 1951 - became one of the most important tools in medicine, vital for developing the polio vaccine, cloning, gene mapping, in vitro fertilization, and more," reads a description on the book's official website. "Henrietta's cells have been bought and sold by the billions, yet she remains virtually unknown, and her family can't afford health insurance."

Rebecca formed a strong friendship with Henrietta and went on to write the New York Times best-selling book.

Oprah, who will also take on a leading role, has been developing the movie for six years after teaming with Six Feet Under and True Blood creator Alan Ball to produce the project.