The stars are aligning in Hollywood on Friday, as celebrities flock together to "Stand Up to Cancer." Jennifer Aniston, James Taylor, Scarlett Johansson, Meryl Streep, David Cook, Christina Applegate, Lance Armstrong, Jack Black, Kirsten Dunst, Charles Barkley, America Ferrera, Halle Berry, Hilary Swank, Forest Whitaker, Jimmy Fallon, and Keanu Reeves are expected to appear at the event.

Diva Mariah Carey will be singing for the cause, along with fellow crooners Beyoncé, Mary J. Blige, Rihanna, Fergie, Sheryl Crow, Miley Cyrus, Melissa Etheridge, Ashanti, Natasha Bedingfield, Keyshia Cole, Ciara, Leona Lewis, LeAnn Rimes and Carrie Underwood. They will be performing "Just Stand Up," the charitable single supporting the cause.

Cancer survivor Christina Applegate will also show her support by attending the telethon, while fellow survivors Sheryl Crow and Melissa Etheridge will perform on "Stand Up to Cancer."

To find out how you can join the cause, click here. "Stand Up to Cancer" airs this Friday on ABC, CBS and NBC.