In addition to HIF1A, HIF2A plays a role in the tumor immune escape mechanism: this isoform enhances expression of stem cell factor (SCF) in ccRCC patients, and upregulation of SCF protein expression promotes secretion of transforming growth factor (TGF)-β and IL-10, thereby forming an immunosuppressive tumor microenvironment and escaping tumor immunity [29]. Here, HIF1A is linked to nonpapillary renal cell carcinoma.