A Cue for Cancer (IMAGE) Rockefeller University Caption To see how the growth signal TGF-beta influences cancer cells, the researchers used a red tag (top) to mark mouse tumor stem cells that received the signal, and a green tag (bottom) to track differences in the stem cells' progeny. Credit Laboratory of Mammalian Cell Biology and Development Usage Restrictions Image may be used only to illustrate research described in the accompanying story. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.