But family relationships are upended when, as girls, the little sister sues her parents to block them from making her give a kidney to her dying sister. Diaz’s character, a former lawyer named Sara, fights her 11-year-old daughter’s attempt at “medical emancipation” in the serious family drama.
The role is far from Diaz’s parts in feel-good movies such as romantic comedy There’s Something About Mary, action-packed Charlie’s Angelesor voicing the role of Princess Fiona in the Shrek animated movies.
Yet Diaz, 36, told Reuters she doesn’t see herself as one kind of actress or another — comedic or dramatic — and she looks to her own youth in working class neighborhoods of Long Beach, California, for lessons in how real life can get messy.

“I don’t feel I’ve ever played the same person twice. Even though I might have done a couple of comedies or a couple of romantic comedies, the characters are all very different to me,” she said.
Nick Cassavetes, son of the late groundbreaking independent filmmaker John Cassavetes, directed My Sister’s Keeper and said he always saw Diaz for more than her bubbly on-screen personality in fluffy Hollywood tales.
“This is a really wonderful actress and over the next few years you’re going to see, she’s going to be borne out to be one of the finest actors of our generation,” he said.