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Figure 1 Effect of tumor necrosis factor-alpha (TNF) (10 ng/ml) on mkk3^–/– (KO) and mkk3^+/+ (WT) hearts during coronary perfusion under conditions of constant pressure. Data represented by mean ± SEM; n = 6 per group. (A) Left ventricular developed pressure (LVDP) before and during 15 min exposure to TNF. (B) Left ventricular volume versus LVDP measured after at least 15 min of TNF. (C) Coronary flow before and during TNF. (D) Upper part shows representative Western blots of total and phosphorylated p38-MAPK and HSP27 in hearts exposed to TNF for 15 min. Activation of p38-MAPK is reflected in the phosphorylation of HSP27. Lower part shows quantitative data expressed as fold increase relative to baseline (mean ± SEM; n = 3). TNF induces a robust activation of p38-MAPK in mkk3^+/+ but not in mkk3^–/– hearts.