Downregulation of H19 imprinted maternally expressed transcript (H19) expression inhibits autophagy in tamoxifen-resistant MCF7 cells; H19 induces autophagy through the S-adenosyl-L-homocysteine hydrolase (SAHH)/DNA methyltransferase 3 beta (DNMT3B) axis, which helps to elucidate the molecular mechanism of tamoxifen resistance in breast cancer (Wang J. et al., 2019). The gene discussed is AHCY; the disease is breast cancer.