Fig.1. Diminished Frs2α expression in Frs2α^cn outflow tract and SHF.

Expression of Frs2α in 0 somite stage (ss) (A) or E9.5 (B) embryos was assessed by immunostaining with anti-FRS2α antibody (green) on paraffin sections. Nuclei were stained with To-Pro3 (red). a1-3, b1-3, and c1-3 were high magnification views of the boxed areas in panels a, b, and c, respectively. Note that in Frs2α^cn/Nkx mutants, Frs2α expression was diminished in ventricular myocardium (V-M), OFT myocardium (OFT-M) and endocardium (OFT-E), pharyngeal endoderm (PE), and splanchnic mesoderm (SM). In Frs2α^cn/Mef mutants, Frs2α expression was disrupted in V-M, OFT-M, and SM, but was intact in the OFT-E and PE.