The mechanism of proliferation in cells of the retinal pigment epithelium (RPE) remains unclear in development.Daring eye development, Microphthalmia-associated transcription factor (MITF), a basic-helix-loop-helix-leucine zipper protein, is expressed at RPE precursor cells and acts as a master regulator for RPE development.Mutations in Mitf such as microphthalmia-vga9 not only cause developmental defects of neural crest stem cell-derived melanocytes in the skin and deafness, but also result in small eyes and retinal degeneration due to abnormalities in RPE differentiation and dysfunction.