Video: Renee Zellweger, Rob Lowe & Celebs Stand Up To Cancer in New PSA

Renee Zellweger, Rob Lowe, Minka Kelly and Kristin Chenoweth are among many others helping to Stand Up To Cancer -- and ET has the details.

SU2C and Comcast are teaming up to bring the hottest celebs and artists in music (Alicia Keys, Justin Timberlake and more) to an On Demand channel that is designed to encourage its audience to help with the fight against cancer. The On Demand channel will also feature a new PSA with Zellweger, Lowe and Chenoweth but ET has a sneak peak!

Check out su2c.org for more on the organization.