HDAC2 and hepatocellular carcinoma: Overall, our results suggest that radiation can inhibit HDAC2 expression, and that the down-regulation of HDAC2 can increase the histone acetylation of the MIR22HG promoter region, thus, increasing the expression of MIR22HG, and thereby increasing the radiosensitivity of HCC through the production of miR-22-5p.