Fig. 4

Disruption of VEGF or calcineurin signaling results in altered expression of notch 1b and bmp4 in cardiac valves. In situ hybridization analysis of the endocardial marker notch 1b (a-d), the myocardial marker bmp-4 (i-l), and the endothelial marker flk-1 (q) in the AV valve region. a: notch 1b was restricted to the AV region of the endocardium in control embryos (see arrow). b: notch 1b was ectopically expressed beyond the AV boundary into the ventricle and weakly in the atrium of embryos treated with AAC 789. c,d: Similar ectopic expression of notch 1b in embryos treated with PTK 787 and FK506, respectively. e-h: Schematic figures for the expression patterns seen in a-d. i: bmp-4 expression was prominent in the in myocardial region of AV valve at 48 hpf in control embryos (see arrow). j: AAC 789 treatment for 4 hr resulted in strong ectopic expression of bmp-4, especially in the ventricle region. k,l: PTK787 and FK 506 induced similar mis-localized expression patterns. m-p: Schematic figures for expression patterns of bmp-4 seen i-l. q: Expression of flk-1 in the endocardium of control embryos at 48 hpf.