Transcription factor involved in anterior and eye development. Promotes the differentiation of both rod and cone photoreceptors cells in the retina. Together with other retinal homeobox proteins, acts as an effector of a cellular clock which, depending on cell cycle progression, establishes the generation of distinct retinal neuronal cell types. Acts synergistically with nrl to activate the rhodopsin promoter (By similarity). Promotes the formation of anterior regions and represses the formation of posterior structures during development. Initially expressed in the Spemann organizer region of early gastrula embryos. Expression then becomes localized to the anterior region; confined to the cement gland anlage at stages 19-25 and localized to the forebrain, optic vesicle and otocyst at stage 28. Expressed at low level from stage 1 to stage 9, when expression levels increase.