NNMT and cancer: Previous studies have reported that NNMT, as a methyltransferase consuming the methyl donor S‐adenosylmethionine (SAM), could decrease the methylation level of protein phosphatase 2A (PP2A), resulting in the activation of MEK/ERK pathway in cancer cells.[17] In this regard, we detected the levels of PP2A methylation and MEK phosphorylation in PRDX6‐overexpressing cells with or without NNMT KD.