To successfully disseminate at sites distant from the primary tumor, cancer cells must be endowed with particular properties.  They must first enter the blood circulation, home to a target organ (like the kidney or the liver),  in which they will establish secondary tumors.  One of the key event during this journey is the ability of the cancer cells to stop in a specific organ before leaving the blood circulation to migrate deep in the tissue of this organ.  This is accomplished by adhesion of the circulating cancer cells to the inside wall of the blood vessels.  Our grant application propose to test the hypothesize that interactions between cancer cells and host cells induces signals in both cell types that are critical for the growth and dissemination of tumors at distant sites.