As observed in cultured cells, immunohistochemical staining in tumor tissues of C57/BL6 wild-type mice subcutaneously inoculated with B16 cells overexpressing green fluorescent protein (GFP) revealed that B16 melanoma cells (GFP positive) expressed APJ protein (Figure 1B); APJ expression was equivalently observed in tumor ECs. The gene discussed is APLNR; the disease is melanoma.