PTGS2 and colonic neoplasm: Growing evidence supports that HIF-2α is involved in angiogenesis.77 HIF2 expression was directly correlated with microvessel density and cyclooxygenase 2 expression in colorectal carcinoma, indicating its potential role in angiogenesis of colorectal carcinomas.53 Selective knockdown of HIF-2α resulted in more pronounced decrease of VEGF and MVD levels compared with HIF-1α repression in colon cancer xenograft studies.