Although the exact sequence of events that couple ASMase-mediated endothelial apoptosis to tumor cure remains under investigation, our preliminary data indicate that microvascular dysfunction signals impairment of homology driven-repair of potentially-lethal DNA DSBs in tumor SCCs ([11], [14], and Thin, Kolesnick and Fuks, unpublished). The gene discussed is SMPD1; the disease is neoplasm.