George Clooney, Gwyneth Paltrow, Will Smith, Denzel Washington and Renee Zellweger are among the celebs who will answer phones at the Sept. 10 “Stand up to Cancer” televised fundraiser.

The stars join the previously announced guests, including Christina Applegate, Lance Armstrong and Cindy Crawford, who will participate in the telecast benefitting research into the disease. ABC, CBS, Fox and NBC are among the nets that will simulcast the commercial-free special, dedicated to the 12 million U.S. cancer survivors.

Neil Diamond, Herbie Hancock and Leona Lewis have signed on to perform, adding to an existing lineup featuring Queen Latifah, Stevie Wonder and Natasha Bedingfield.

The American Association for Cancer Research, made up of 32,000 scientists and led by Nobel Laureate Dr. Phillip A. Sharp, will administer and manage grants resulting from the fundraiser. Cat Deeley of Fox’s “So You Think You Can Dance” will host the pre-show web kick-off before the celeb phone bank opens at 7:30 p.m. EST. A 30 minute online “after hours” extended play featuring jams with guests Bedingfield, Orianthi, Fitz and the Tantrums and Ann and Nancy Wilson of Heart will conclude the evening’s events.

The 2008 telecast helped raise more than $100 million. Viewers can donate via text, online and on a dedicated phone line.