Gli2 is required for the Shh effects on proliferation and cell fate. Retinal explants were cultured from wild-type (Wt; n = 3) and Gli2^−/− (n = 3) mice at E18 for 3 d in culture with or without a Smo agonist. IHC was performed on dissociated cells using anti-BrdU, anti-CRALBP, anti-rhodopsin, and anti-recoverin antibodies. Values represent the fold induction of positive cells in Wt + Ag or Gli2^−/− + Ag cultures compared with nontreated explants. Error bars represent SEM. *, P < 0.05; **, P < 0.01.