| HDAC 1 , a histone deacetylase , forms a complex with Hus 1 and Rad 9 , two G2 / M checkpoint Rad proteins . ^^^ Human HDAC 1 was found to interact specifically in yeast , mammalian cells , and in vitro with the human Hus 1 gene product , whose Schizosaccharomyces pombe homolog has been implicated in G ( 2 ) / M checkpoint control . ^^^ Both HDAC 1 and Hus 1 proteins localize to the nuclei . ^^^ Furthermore , HDAC 1 and Hus 1 were found to exist in a complex with Rad 9 , a known Hus 1 interacting factor . ^^^ |