Chromatin immunoprecipitation of (A) acetylated lysine 9 (K9) of histone H3 and (B) methylated K9 of histone H3 in HeLa, HL-60, HL-60 + PMA, 3T3 and RAW 264 cells with quantification of recovered DNA at 6 and 5 points along the human and murine c-FMS locus, respectively. The location of the promoter, FIRE-1 kb and FIRE regions are indicated (P, F-1kb and F) and DNA was quantified as described in Materials and Methods. Differentiation of HL-60 cells with PMA induces a marked increase in H3 K9 acetylation upstream and downstream of FIRE while FIRE remains under-acetylated. A similar pattern of H3 K9 acetylation is seen in RAW 264 cells. Both HL-60 and HeLa H3 are methylated at K9 across the locus while PMA differentiation of HL-60 cells induces H3 K9 demethylation.