POLD1 and hepatocellular carcinoma: In the present study, serum pharmacological methods, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, flow cytometry and fluorescence quantitative polymerase chain reaction (PCR) were used to determine the effects of bock greenbrier rhizome on human hepatocellular carcinoma (HCC) cell growth and the expression of DNA polymerase δ catalytic subunit gene 1 (POLD1).