Many of these genes correlated positively with the HIF metagene in multiple tumor-specific datasets, including the canonical HIF target genes ALKBH5, BNIP3, EGLN3, GAPDH, P4HA2, PDK1, PFKL, PFKP, PLOD1, and TPI1. This co-variation of the HIF metagene with other HIF target genes confirms an underlying biological variation in HIF metagene expression within each tumor type. This evidence concerns the gene P4HA2 and neoplasm.