Mesh : Animals Basic Helix-Loop-Helix Transcription Factors Basic-Leucine Zipper Transcription Factors Bone Morphogenetic Proteins / physiology Cell Differentiation / genetics DNA-Binding Proteins / physiology Eye Proteins / physiology Fibroblast Growth Factors / physiology Genes, Homeobox / physiology Hedgehog Proteins / physiology Homeodomain Proteins / physiology Humans Intercellular Signaling Peptides and Proteins / physiology Orphan Nuclear Receptors PAX6 Transcription Factor Paired Box Transcription Factors Receptors, Cytoplasmic and Nuclear / physiology Repressor Proteins / physiology Retina / cytology embryology Retinal Degeneration / etiology Transcription Factors / physiology Vertebrates / embryology Wnt Proteins