When the MCF-7/Adr cells (transduced with the GV248 lentiviral vectors) expressing shRNA targeting ID4 or non-targeting controls were subcutaneously implanted into the immunocompromised mice, we observed a significant decrease in tumor formation and an increase in Adriamycin sensitivity and the growth of tumor bearing mice when ID4 was inhibited (Fig 6A, 6B, 6C). The gene discussed is ID4; the disease is neoplasm.