Effect of HPCs on histone acetylation in MEL cells. (A) MEL cells were cultured with TSA (75 nM), HMBA (5 mM), and SAHA (2.5 μM) for the indicated times. Histones were extracted from the treated cells and were analyzed on an AUT gel. (B) MEL cells were cultured for 6 h with no addition (lane 1), 5 mM HMBA (lane 2), 0.3 mM EMBA (lane 3), 30 μM SBHA (lane 4), 2.5 μM SAHA (lane 5), and 4.0 μM CBHA (lane 6). Histones were isolated and analyzed on an AUT gel. The degree of histone acetylation of histone H4 is indicated as follows: Ac0, nonacetylated H4; Ac1, monoacetylated H4; Ac2, diacetylated H4; Ac3, triacetylated H4; Ac4, tetraacetylated H4.