HIF1A and nonpapillary renal cell carcinoma: Gordan et al. reported an alternative classification of sporadic ccRCC based on the VHL allele, HIF1a, HIF2a, and MYC expression, recognizing three different molecular subgroups: VHL WT (wild-type VHL alleles, undetectable HIFα protein), H1H2 (VHL-deficient, expressing HIF1α and HIF2α proteins) and H2 tumors (VHL-deficient, expressing only HIF2α, enhanced MYC activity, higher proliferation rates) [72].