Of the 15 RCC tumour tissues, 12 had high methylation of PON1, and the representative images were presented in Figure 3A. Moreover, compared with the kidney normal cell line HK‐2, PON1 was hypermethylated in 786‐O, Caki‐2, and SKRC39 cell lines (Figure 3B). The gene discussed is PON1; the disease is renal cell carcinoma.