Given the disparate effects that HIF-1α and HIF-2α may induce on tumor growth and progression, it will be critical to determine whether potential HIF inhibitors affect both HIF-α subunits equally, particularly in cancers that express both HIF-1α and HIF-2α, such as colon cancer, where these isoforms appear to play distinct roles. This evidence concerns the gene HIF1A and malignant colon neoplasm.