Whereas MDA-MB-231 cells proliferated extensively when cultured alone, growth of tumor cells co-cultured with HUVECs was markedly suppressed as indicated by the decrease in tumor cell count and percentage of Ki67-positive tumor cells as well as by an increase in p27-positive cells while cell viability as detected with 7-amino actinomycin D (7-AAD) was unchanged (Fig. 1A-E). The gene discussed is MKI67; the disease is neoplasm.