the present invention provides for identification of agents that induce growth arrest and survival of cancer cells , which remain dormant in bone marrow , thus preventing their eradication through use of standard chemotherapy or radiation therapy . basic fibroblast growth factor , a mammary differentiation factor abundant in the bone marrow stroma , induces growth arrest of relatively differentiated breast cancer cells and restricts their survival to fibronectin by upregulating integrin α5β 1 . most of the fgf - 2 - arrested cells fail to establish optimal ligation to fibronectin and undergo cell death . cells that do attach to fibronectin , another major constituent of the bone marrow microenvironment , stay alive and growth - arrested for many weeks . using function - blocking antibodies and peptides , a specific contribution of α5β1 - fibronectin interaction in maintaining survival of growth - arrested cells was demonstrated . the present invention thus allows for methods , agents and pharmaceutical compositions that can be used to potentiate the activity of chemotherapy or radiation therapy .