ATF6 and hepatocellular carcinoma: According to the results of this study, we could conclude that: (a) baicalin inhibits human HCC cells by inducing apoptosis; (b) baicalin induces cell apoptosis by activating ATF6 signaling pathway in ER stress; (c) S2P, rather than S1P is the molecular target for baicalin in inducing ER stress‐mediated HCC cell apoptosis.