PIN1 and hepatocellular carcinoma: Besides Wei et al. demonstrated that ATRA-induced Pin1 ablation inhibits triple-negative breast cancer cell growth (Wei et al., 2015), Liao et al. also reported the anti-tumor effect of ATRA in hepatocellular carcinoma (HCC) in vitro and in vivo (Liao et al., 2017; Yang et al., 2018).