CCND1 and hepatocellular carcinoma: To further determine the effect of miR-520b targeted MEKK2 or cyclin D1 on growth of hepatoma cells in vivo, the HepG2 cells transiently transfected with siRNAs targeting MEKK2 or cyclin D1 were subcutaneously injected into 4- to 6-week-old BALB/c athymic nude mice.