Fig. 1.

Generation of cardiomyocyte-specific STAT3-deficient mice. (A) Schematic representation of STAT3 alleles. (B) Detection of Cre recombinase in cardiomyocytes using Z/AP double reporter mice (see text for details). (C) Ablation of STAT3 protein in cardiac myocytes. Twenty micrograms of protein extract was used for Western blot analysis. (D) Dilated hearts in cardiac-specific STAT3 knockout mice. The hearts from 9-month-old WT (+/+), heterozygous (C/F/+), and STAT3-deficient mice (C/F/D) were excised (Upper). Cross sections through the same hearts are shown (Lower). (E) Heart (g)/body (kg) weight ratio was calculated in all genotypes mice grouped by age (<7 months and ≥7 months) and t test was performed. Difference was shown between the homozygous and heterozygous (P = 0.04) and homozygous and WT (P = 0.02) mice older than 7 months.