HDAC1 and hepatocellular carcinoma: Considering that the expression of HDAC-1, -2 is up-regulated in HCC, their combined inhibition was proposed by Zhou et al. According to their results, there was an increased expression of p21Waf/Cip1 and p19INK4d, which lead to decreased expression of cyclin-dependent kinases (CDKs), cell cycle blockage and apoptosis [44].