HDAC1 and hepatocellular carcinoma: In contrast, levels of HDAC1, Pan- H3 phosphorylation, (p-H3), and tyrosyl-DNA phosphodiesterase (TDP1) were decreased in a time-dependent manner resulting in enhanced DNA damage in HCC cell lines (HepG2) [93,94,95,96], suggesting that a decrease in TDP1 levels accompanied high levels of γH2AX.