Pressure overload causes more apoptosis in the inflammatory lesions of MEKK1^–/– mice than in those of MEKK1^+/+ mice. MEKK1^+/+ (control) and MEKK1^–/– mice were subjected to aortic banding for 7 days. DAPI staining (a and b) and TUNEL staining (c and d) in LV myocardium 7 days after aortic banding. White arrows indicate TUNEL-positive myocyte nuclei in a control mouse (a and c) and in a MEKK1^–/– mouse (b and d). Bar = 100 μm. (e) TUNEL-positive cells in the inflammatory lesions in LV myocardium. More TUNEL-positive cells were observed in the inflammatory lesions of MEKK1^–/– mice than in those of control mice. *P < 0.05.