Knocking down PDK1 sensitizes HCC cells to radiotherapy: 2 Gy irradiation combined with siPDK1 reduces Mahlavu cell viability from 42% to 3% and inhibits clonogenicity by 91%, while Huh7 cell clonogenicity is suppressed by 99.8%. The gene discussed is PDK1; the disease is hepatocellular carcinoma.