Expressions of p300 and CBP in embryonic hearts during chamber formation and septation stages from E10.5 to E15.5. E10.5 embryo heart shows a high p300 expression (A) and a relative low expression of CBP (B) in most cardiac compartments, in particular in the trabeculae (arrow) and ventricular myocardium (arrowhead). C shows a high expression of p300 at E11.5 in atria and ventricle walls (arrowhead), ventricular trabeculae (arrow). D shows that a high expression of CBP was found at E11.5 in atrioventricular myocardium (arrowhead), a relatively low expression of CBP was found in trabeculae (arrow) and OFT. At E12.5, p300 is highly expressed in atria and ventricle walls (arrowhead), ventricular trabeculae (arrow)(E). A similar CBP expression pattern is shown in E12.5 embryos (F) in cardiac walls (arrowhead) and trabeculae (arrow). In E14.5 embryonic heart, p300 is highly and extensively expressed in walls, ventricular trabeculae, muscular IVS and nascent membranous IVS, nascent pulmonary artery and aorta (G). At the same stage, CBP is highly expressed in atrioventricular myocardium and lowly expressed in atrioventricular valves, trabeculae and OFT (H).