We then mutated both lysine 23 and 210 residues of NNMT‐GFP to arginine simultaneously (K23R/K210R), and found the K23R/K210R double mutation of NNMT markedly impeded the reduction of NNMT protein level caused by PRDX6 KO in ovarian cancer cells (Figure 4G). Here, NNMT is linked to ovarian carcinoma.