Fig. 2. Overexpression of miR302-367 cluster in the developing heart results in increased cardiomyocyte proliferation and cardiomegaly. Overexpression of miR302-367 cluster in the developing heart results in increased cardiomyocyte proliferation and cardiomegaly. (A) At E18.5, Nkx2.5cre:R26R-miR302-367Tg/+ mutants have an enlarged heart with thickened ventricular myocardium and ventricular septal defects compared to Nkx2.5cre controls. (B) Cardiomegaly and increased cardiomyocyte proliferation in Nkx2.5cre:R26R-miR302-367Tg/+ mutant hearts at P20. (A and B) Immunostainings for PH3 and α-actinin and wheat germ agglutinin (WGA) show the number of mitotic cardiomyocytes. Scale bars, 100 μm. High-magnification reveals PH3+ cardiomyocytes. LA, left atrium. Data are means ± SEM (n = 3). P values determined by Student’s t test. Ying Tian et al., Sci Transl Med 2015;7:279ra38 Copyright © 2015, American Association for the Advancement of Science