PGP and hepatocellular carcinoma: One primary driver of the limited therapeutic response of DOX delivered by HAI is the expression of p-glycoprotein (P-gp) in hepatocellular carcinoma.[8,9] The reliance on free diffusion to achieve high intracellular concentrations of DOX creates a large gradient within the cell of DOX, with the highest concentration being at or near the cell surface where P-gp is located.