A previous study on HCC, however, showed that even though PD-L1 was frequently expressed in stem cell features of HCC, the presence of PD-L1 was positively associated with cytokeratin 19 (CK-19) and Sal-like protein 4 (SALL-4), but not with EpCAM [36]. Here, SALL4 is linked to hepatocellular carcinoma.