MiR-34a-5p regulates the expression of Sirtuin 1 (SIRT1), P-glycoprotein (P-gp), and multidrug resistance-related protein 1 (MRP1) by directly binding to the 3′untranslated region (UTR) of SIRT1, thereby reversing the MDR of GC cells (Deng et al., 2021). The gene discussed is SIRT1; the disease is gastric cancer.