Critical elastic fiber assembly components are down-regulated in saccular stage inhibitory κB kinase β transactivated (IKTA) lungs. A: Gene expression of critical elastin assembly components in embryonic day (E) 18 and postnatal day (PN) 2 control (CTRL) and IKTA lungs, as measured by quantitative RT-PCR. B: Ontogeny of expression of Fbln4, Fbln5, Loxl1, and Fbn1 during lung development in wild-type mice. C and D: Western blot analysis of lung tissue homogenates for fibulin-5 protein in E18 and PN2 lungs. Representative Western blot images (C) and densitometry analysis (D). Data are expressed as means ± SEM. n = 4 per group. ∗P < 0.05 versus E18 controls (A), for expression of Fbln5 and Loxl1 at PN1 versus expression at E15 (B), and for fibulin-5 protein expression versus expression in E18 control lungs (C and D); †P < 0.05 versus PN2 controls (A), for expression of all four genes at PN5 versus expression at E15 (B), and for fibulin-5 protein expression versus expression in PN2 control lungs (C and D); ‡P < 0.05 for expression of Fbln5, Loxl1, and Fbn1 at PN14 versus expression at E15 (B); and §P < 0.05 for expression of Fbln5 in adult lungs versus expression at E15 (B).