Mitochondrial and reticular Nix are equally effective in causing in vivo cardiomyopathy. (A) Nix immunoblot analysis of heart homogenates. (B) Mutant Nix localization to cardiac subcellular fractions. (C) TUNEL assays (n = 5 hearts per group). (D) Echocardiographic left ventricular end-diastolic dimension. (E) Echocardiographic left ventricular fractional shortening (n = 26 tet off controls, n = 6 Nix-WT, n = 12 Nix-ActA, n = 10 Nix cb5). (F) Left ventricular peak positive dP/dt as a function of dobutamine infusion dose (n = 9 tet off controls, n = 5 Nix-WT, n = 5 Nix-ActA and n = 4 Nix cb5). *, P < 0.05 compared with tet off control.