Shh activation of Hes1 and Hes5 is independent of Notch signaling. Retinas at P0 were electroporated with SMO-M2 cotransfected with pUB-GFP or pUB-GFP alone and cultured for 3 d with DAPT or DMSO control. (a–d) GFP fluorescence localizes the transfected cells. ISH was performed for Gli1 (e–h), Hes1 (i–l), and Hes5 (m–p). Differences in the localization of transfected cells within the explants are caused by folding and twisting during tissue processing. Bars, 100 μm. (q) Retinal explants (P0 + 3 days in vitro [DIV]) were electroporated with Smo-M2/pUb-GFP, treated with DAPT, dissociated, and scored for the proportion of BrdU+GFP+/GFP+ cells. The magnitude of Smo-M2–induced proliferation is not changed with DAPT treatment. Error bars represent SEM. *, P < 0.05; **, P < 0.005.