HIF-1α is overexpressed in many types of cancer and its overexpression correlates with chemo- and radiotherapy resistance.45, 46, 47 Therefore, HIF-1α has been considered to be a therapeutic target in cancer treatment.37 To investigate the potential of HIF-1α as a therapeutic target for the treatment of HTLV-1-infected T cells, chetomin, which inhibits the HIF-1α transactivation activity by blocking the interaction of HIF-1α with its cofactor p300,30 was used in our experiments. The gene discussed is HIF1A; the disease is cancer.