Figure 1. Endogenous Ikbkap expression in the retina. Representative LacZ staining on Ikbkap:β-gal retina or β-galactosidase IHC images are shown. A, At E15.5, Ikbkap expression was detected in developing RGCs in the GCL. N, nasal; T, temporal. B, P7 retina showed strong expression in the GCL. There was no regional bias or asymmetry in the expression pattern. C, At 1 month, RGCs, amacrine cells, subset of bipolar cells, and photoreceptors (IS and outer plexiform layer) expressed IKAP. D, At 1 month, antibody staining showed the same pattern of Ikbkap expression as LacZ staining. E, All RGCs (RBPMS+, green) expressed Ikbkap (red; bottom). F, Many amacrine cells (AP2α+) expressed Ikbkap (red; arrowheads). G, A subset of bipolar cells (Otx2+ in INL) expressed Ikbkap (red; arrows). H, Müller glial marker Sox2 (green) did not colocalize with β-gal (red; arrows), suggesting that they do not express Ikbkap. Some of the Sox2+ amacrine cells expressed Ikbkap (arrowheads). NBL, neuroblastic layer. Scale bars, 1 mm (A, top), 50 μm (A, bottom), 500 μm (B), 250 μm (C, top), 25 μm (C, bottom), and 50 μm (D–H).