ATF6 and hepatocellular carcinoma: Consistently, in PPM1H knockdown cells, co-transfecting ATF6 plasmids barely altered the migration and invasion of Hep-G2 and Huh-7 cells (Figures 2C, 2D, S4C, and S4D), indicating that ATF6 regulates the proliferation and metastasis of hepatoma cells through the function of PPM1H.