NNMT and hepatocellular carcinoma: In the present study, we found that activated HSCs upregulated NNMT expression levels in hepatoma cells, based on our previous study and other reports, which is most likely the result of TGF‐β secretion by the HSCs (Campagna et al., 2018; Coulouarn and Clement, 2014; Liang et al., 2018).