News Life Rare observations of metastasis in real time Videos show how cancer cells move and spread By Tina Hesman Saey December 8, 2009 at 12:53 pm - More than 2 years ago Share this:Share Share via email (Opens in new window) Email Click to share on Facebook (Opens in new window) Facebook Click to share on Reddit (Opens in new window) Reddit Click to share on X (Opens in new window) X Click to print (Opens in new window) Print SAN DIEGO — A growth factor helps cancer cells get a move on, a new study shows. Breast cancer cells (in mice), shown in green, individually peel off from the main tumor when they get a “go” signal from a type of growth factor.