When we investigated the levels of HIF-1α and HIF-2α proteins in vGPCR murine tumors and KS biopsy specimens by immunohistochemical analysis, we found that both vGPCR murine tumors and human KS showed a remarkable overexpression of these transcription factors, compared to normal skin (results not shown) (Fig. 3C). The gene discussed is HIF1A; the disease is Kaposi's sarcoma.