NCI -- Scientists using a three-dimensional cell culture system have identified a mechanism by which dormant, metastatic tumor cells can begin growing again after long periods of inactivity. The new findings indicate that the switch from dormancy to proliferative, metastatic growth may be regulated, in part, through signaling from the surrounding microenvironment, which leads to changes in the skeletal architecture of dormant tumor cells. Targeting this mechanism may also provide strategies for inhibiting the switch from dormancy to proliferation. The results of this study by National Cancer Institute (NCI) scientists and their collaborators, appears in the August 1, 2008, issue of Cancer Research. NCI is part of the National Institutes of Health.