Some of the biggest female singers on the planet have gotten together to record vocals for a star-studded single called "Just Stand Up," benefiting the Stand Up to Cancer campaign. The unprecedented gathering features vocals from Mariah Carey, 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. The tune is being produced by the powerhouse duo of Kenny "Babyface" Edmonds and Antonio "L.A." Reid, who are working together for the first time in nearly 20 years on the track.

The song will be available for purchase exclusively on iTunes on September 2 and will get its TV premiere on September 5 during the live "Just Stand Up" special, which will air simultaneously and commercial-free on CBS, ABC and NBC. According to a press release announcing the project, the song was conceived by Reid, the chairman of the Island Def Jam Music Group, after a meeting with the women behind the Stand Up to Cancer campaign.

Among the stars confirmed to either appear or answer phones on the TV broadcast so far are: Casey Affleck, Jennifer Aniston, Christina Applegate, Lance Armstrong, Abigail Breslin, Josh Brolin, David Cook, Dana Delany, Fran Drescher, Julia Louis-Dreyfus, Kirsten Dunst, Elizabeth Edwards, Jon Favreau, America Ferrera, Neil Patrick Harris, Salma Hayek, Scarlett Johansson, Masi Oka, Danica Patrick, Christina Ricci, Robin Roberts, Homer Simpson, Marge Simpson, Meryl Streep, Hilary Swank, Charlize Theron, Goran Visnjic, Forest Whitaker and Reese Witherspoon.

The show will also feature network news anchors Charles Gibson, Katie Couric and Brian Williams, who will report on potentially life-saving research and speak with cancer patients and scientists.