NNMT and breast cancer: Specifically, Parsons et al. observed that NNMT expression and its product 1-methylnicotinamide could protected SH-SY5Y neuroblastoma cells from the toxicity of the Complex I inhibitors MPP + (1-methyl-4-phenylpyridinium ion) and rotenone (Parsons et al., 2011), and Wang et al. showed that ectopic overexpression of NNMT significantly decreased the cancer-killing effects of adriamycin and paclitaxel by stabilizing SIRT1 protein in breast cancer cells (Wang et al., 2019).