PGP and hepatocellular carcinoma: At higher doses a slight inhibitory effect on cell proliferation, administration of DOX with ECG at lower doses significant inhibition of cell proliferation in vitro and hepatoma growth in a xenograft mouse model, increase in DOX and Rh-123 accumulations, decreasing P-gp in cells concurrently treated by DOX and ECG, reduction of the expression of MDR1 mRNA in BEL-7404/DOX cells treated by DOX and ECG