PDCD1 and hepatocellular carcinoma: In addition, PD-1-deficient GPC3-CAR T cells significantly increased the phosphorylation of Akt and expression of the antiapoptotic protein Bcl-XL, thus preventing the depletion of PD-1-deficient GPC3-CAR T cells from confronting hepatocellular carcinoma cells expressing natural PD-L1 (112).