Loss of co-repressor complex integrity and increased histone acetylation in Hdac1/2 knock-out thymocytes. Experiments were performed on thymocytes isolated from 6- to 8-week-old mice. (A) Quantitative Western blot data for the indicated proteins. White and black bars denote protein levels measured in wild-type or knock-out cells, respectively from the indicated genotypes. Blots were quantified using a LiCOR scanner and normalized to the level of α-tubulin. Relative protein expression is presented as % of LMCs. Mean values (n = 3) ± SEM are plotted. (*P < .05, ***P < .001, paired t test). (B) Deacetylase activity was measured using a commercially available kit using 2μg of nuclear extract (left), or from individual HDAC1/2 containing complexes immunoprecipitated using anti-sera to Sin3A, or MTA2 as indicated. Nuclear extracts were prepared from thymocytes of the indicated genotype. (C) Western blot data for the indicated proteins co-immunoprecipitated in panel B. (D) Quantitative Western blotting was used to determine the levels of global histone acetylation. Acetylation levels were normalized to the total amount of H3 quantified using a LiCOR scanner. Mean values (n = 3) ± SEM are plotted. (*P < .05, **P < .01, paired t test).