In the case of tumors that develop from np2 expressing MDA-MB-435 cells, we found that the expression of sema3A and sema3D reduced the concentration of blood vessels in resulting tumors by 65% (Fig. 6E) even though tumor development from these cells was not inhibited at all by sema3A (Fig. 3B). The gene discussed is SEMA3D; the disease is neoplasm.