(a) H2AX−/− MEFs expressing H2AXwt or H2AXK36R were irradiated (5Gy) and allowed to recover. γH2AX and H2AX were monitored by western blot. (b) 293T cells expressing Flag-H2AX were incubated with TSA (0.4 μM) or nicotinamide (NIA: 10mM) for 8hr. H2AX and H2AXK36Ac were monitored using antibody AbK36Ac. (c) 293T cells expressing Vector, Flag-H2AXwt or Flag-H2AXK36R were untreated or exposed to TSA (0.4μM for 8hr) and immunoprecipitated with Flag antibody. H2AXK36Ac was monitored by western blot using AbK36Ac. (d) Histones from H2AX+/+ MEF cells were immunoprecipitated with IgG or AbK36Ac. H2AX was detected by western blotting. (e) 293T cells were transiently transfected with Flag-H2AX and either vector, Flag-PCAF, Flag-GCN5, HA-CBP, HA-p300 or HA-Tip60. 72hr later, chromatin associated histones (upper panel) and total proteins (lower panel) were extracted. Acetylation of lysine 36 was detected with AbK36Ac antibody, and expression of HATs was monitored with anti-Flag or anti-HA antibody.