MTOR and nonpapillary renal cell carcinoma: The PI3K/AKT/mTOR signaling pathway serves an important role in ccRCC pathogenesis and progression, and is negatively regulated by the tumor suppressor PTEN. PTEN has been identified as one of the most commonly lost or mutated tumor suppressor genes in human cancers (Que et al., 2018; Tang et al., 2017); however, although PTEN has been thoroughly investigated in RCC, its prognostic role remains controversial.