Fig. 5. Attenuated MMP9 and MMP2 expression in SM22-Cre;R26R;Bmpr1a^flox/flox mouse embryos. (A) Profiling by qRT-PCR the expression of genes that might be modified by the SM22-targeted deletion of Bmpr1a. Values are shown relative to 18S RNA. n=3 where each sample combines 3-4 embryos. ^*P<0.05. Eln, elastin; Colla1, collagen Ia1. (B) Reduction of MMP9 (b versus WT in a) and MMP2 (d versus WT in c) protein expression in aortic walls of flox/flox embryos as assessed by immunofluorescence. Note the absence of immunoreactivity in an aortic section of a WT incubated with only the secondary antibody as a negative control (e). Panels depict WT and mutants at the same magnification. Scale bar: 50 µm.