APAF1 and renal cell carcinoma: Notably, numerous TSGs were also reported to be hypermethylated in RCC samples compared to normal tissue (APAF-1, APC, BTG3, CDH1, Gamma-catenin, GATA-3, HOX-B-13, KILLIN, RARβ2, RASSF1A, TIMP3, VHL, and others), associating with increased tumor cell proliferation, invasion, and metastization (Morrissey et al., 2001; Nojima et al., 2001; Dulaimi et al., 2004a; Hoque et al., 2004; Shinojima et al., 2006; Shenoy et al., 2015).