PDCD1 and hepatocellular carcinoma: To test whether MHCC97H cells may negatively regulate MET-CAR-T cell activity through PD-L1/PD-1 interaction, we co-cultured MHCC97H cells with NT and MET-CAR-T cells generated from HS (n = 6) or HCC patients (n = 5) for 3 days, then analyzed PD-1 expression in MET-CAR-T cells using flow cytometry.