The CPEB1 mutant (S174A, S180A) (CPEB1-AA) reduces, but does not abolish, retinal ganglion cell (RGC) differentiation. (A) Cells transfected with CPEB1-GFP classified into the six retinal cell types according to layering and morphology; no differences were observed. (B) Examples of cells in the RGC layer transfected with CPEB1-RBM-GFP (RBM) or CPEB1-AA-GFP (AA) that are positive for Isl-1 staining. Blue, DAPI; green, GFP; red, Isl-1. In each image, the upper and lower dotted lines indicate the outer and inner plexiform layers, respectively. The upper and lower solid lines indicate the apical and basal limits of the retina, respectively. Numbers in or above bars indicate number of cells counted. (C) Fewer cells in the RGC layer transfected with AA express Isl-1 compared to RGCs transfected with RBM. However, approximately half of AA-expressing cells still express Isl-1. Scale bars 5 μm. Abbreviations: A, amacrine cell; BP, bipolar cell; GCL, ganglion cell layer; H, horizontal cell; INL, inner nuclear layer; M, Müller cell; ONL, outernuclear layer; PR, photoreceptor; RPE, retinal pigment epithelium.