STAT3 and hepatocellular carcinoma: According to the IC50 of HCC cells and the preliminary experimental results of STAT3 phosphorylation assay, we determined the concentrations of stattic in the subsequent studies for different cell lines, and the dose of X-ray in different experiment was determined according to the results of pretest, such as 2 Gy in STAT3 phosphorylation assay, 4 Gy in wound-healing and transwell assay, and 8 Gy in apoptosis analysis.