LOS ANGELES — George Clooney, Will Smith and Gwyneth Paltrow will join an impressive list of stars taking part in September's "Stand Up to Cancer" telethon airing on major networks.

Other celebrities announced Wednesday include Denzel Washington, Renee Zellweger, Kathy Bates and Richard Branson. Kareem Abdul-Jabbar, Lance Armstrong and Elizabeth Edwards were previously announced as participants.

Performers will include Green Day's Billie Joe Armstrong, Neil Diamond, The Edge, Herbie Hancock, Lady Antebellum and Leona Lewis. Queen Latifah, Martina McBride and Stevie Wonder were among those already announced.

Clooney, in particular, is a fundraising heavyweight. At Sunday's Emmy Awards, he accepted the Bob Hope Humanitarian Award for efforts on behalf of victims of this year's earthquake in Haiti, the 2004 tsunami in Indonesia and the Sept. 11 attacks.

"Stand Up to Cancer" is aimed at raising money to speed up innovative cancer research, according to movie producer Laura Ziskin ("Spider-Man"), who is a cancer survivor and co-founder of the Stand Up to Cancer group.

The telethon is returning for a second time after the 2008 event helped deliver more than $100 million for research.

This year's telethon will be simulcast commercial-free (8 p.m.-9 p.m. ET) on Sept. 10 by U.S. television networks ABC, CBS, Fox and NBC as well as a variety of cable channels.

"A donation of any size brings scientists one step closer to a cure," Ziskin said in a statement Wednesday. All public donations go to cancer research, the group said.

The American Association for Cancer Research, the scientific partner of Stand Up to Cancer, administers grants and provides scientific oversight in partnership with a Stand Up to Cancer advisory committee.

Stand Up to Cancer is a program of the Entertainment Industry Foundation, a nonprofit TV and film industry group that supports programs addressing health, education and social issues.

Telethon viewers will be asked to pledge donations by phone or on the Stand Up to Cancer website.