Isl2-GFP+expression mimics endogenous Isl2+expression. (A and B) Immunofluorescent staining for Isl2 expression (red) in the GCL of P8 Isl2-GFP mice (A, green) and Isl2-LacZ knock-in mice (B, green) reveals a high degree of co-localization (arrows), although a few Isl2+ cells are not GFP+ (arrowhead). bar, 50 μm. (C and D) Immunofluorescent staining for vesicle-associated choline acetyl transferase (VA-ChAT) (C, red) or ChAT (D, red) in P15 Isl2-GFP (C) and Isl2-LacZ knock-in (D) retinas reveals a similar pattern of dendritic arborization in the inner plexiform layer. bar, 50 μm. (E) Quantification of fluorescence intensity signal for VA-ChAT (red) and GFP through the IPL of a representative Isl2-GFP retina.