JAK1 and hepatocellular carcinoma: Mechanistically, the epithelial-to-mesenchymal transition (EMT) enriches PD-L1 in CSCs through the EMT/β-catenin/STAT3/PD-L1 signaling axis (22). In hepatocellular carcinoma, IL-6 was shown to activate phosphorylation of PD-L1 on Tyr112 by Janus kinase 1 (JAK1) and then recruit the endoplasmic reticulum-associated N-glycosyltransferase STT3A to maintain PD-L1 stability (73).