Hollywood’s A-list celebrities are participating in a novel anti-cancer campaign on Twitter.

Stand Up to Cancer on Twitter, or SU2C, has hidden tee-shirts that have been autographed by A-listers in more than 20 cities around the nation.

Stars reported to be joining the Twitter hunt include Jennifer Aniston, Jack Black, Kirsten Dunst, Scarlett Johansson and Josh Groban.

They will tweet clues on the whereabouts of the booty to add to those already posted on the site.

The SU2C Twitter page is a swirl of bright orange and yellow that uses the group’s hip logo.

It features star wattage “@ names” tweeting, though the identities behind the sign-ins are not confirmed.

SU2C is marking a one-year anniversary with the hunt and says its mission is to speed up patient access to new treatments by bringing together the best and the brightest in the cancer community.

Source: Splash News

Two of Twitter’s most famous users, Demi Moore and Ashton Kutcher, have expressed concern about the site’s potential for stalkers if a proposed reality show goes ahead.

“I don’t want to be stalked!” wrote Kutcher on the site.

“It’s all fun and games until someone gets stalked,” he continued.

Kutcher’s tweeting drew worldwide attention when he posted photos of Moore apparently while she was steaming his clothes.

Twitter has this week reportedly announced it is working with Brillstein Entertainment Partners to develop an unscripted series based on the site that would have competitors trail celebrities in an interactive format.

Moore reportedly wrote that she hoped the news wasn’t true: “If it is, our Twitter time may come to quick and sad end!”