On-bipolar cells are labeled in Isl2-GFP mice. (A-C) Immunofluorescent staining of the rod bipolar marker PKCα reveals a high degree of co-localization in Isl2-GFP+ cells (arrows). bar, 50 μm; (D-F) Immunofluorescent staining for the On-bipolar marker GOα reveals co-expression in all GFP+ cells in the INL. bar, 50 μm; (G-I) Immunofluorescent staining for the Off-bipolar marker Bhlhb5 reveals no co-localization with GFP+ cells in the inner nuclear layer. bar, 50 μm.