H7, an inhibitor of serine kinases, induces apoptosis and the reduction of activated STAT3 and Mcl-1 expression in macrophages. (A-B) Macrophages were treated with H7 (50 μM) for 24 hours. The cells were collected and analyzed for mitochondrial integrity by Rh123 retention (mean fluorescence, % control, panel A), and apoptosis defined by DNA fragmentation (% < 2N DNA, panel B). ** indicates P < .01 determined by Student t test for paired samples compared with control. The results (mean ± 1 SE) of a single experiment, performed in triplicate, are presented, which are representative of 2 experiments. (C) H7 treatment inhibits STAT3 Ser⁷²⁷ phosphorylation (Phospho-Ser STAT3) and Mcl-1 expression in primary macrophages. Macrophages were treated with H7 (50 μM) for 24 hours. Cells were harvested for Western blot analysis, probing with antibodies to Ser⁷²⁷-phosphorylated STAT3 and to Mcl-1.