Curves are based on data from several studies on the developing rat retina: Crx, cone-rod homeobox [86]; Irbp, interphotoreceptor retinol-binding protein or retinol binding protein 3 [125]; Otx2, orthodenticle homeobox 2 [86]; Pax4, paired box 4 [76]; Pax6, paired box 6 [76]; Pdc, phosducin or MEKA [122]; Rax, retina and anterior neural fold homeobox [9]; Rho, rhodopsin or opsin [126]; Rhok, rhodopsin kinase or G protein-coupled receptor kinase 1 [123]; Sag, S-antigen or arrestin [122]