PDCD4 and hepatocellular carcinoma: Studies indicated that resveratrol (Li et al., 2014), matrine (Luo et al., 2017), oxymatrine (Huang et al., 2014), and ursolic acid (Liu et al., 2015) all reduced miR-21 expression in HCC cells, inhibiting proliferation and promoting apoptosis, suggesting their involvement in the lncRNA GAS5/miR-21/PDCD4 pathway for anti-HCC action.