The prospero gene is expressed specifically in R7 and cone cells of the eye disc. This expression is transcriptionally dependent on signaling through EGFR which also signals within eye disc cells that do not express prospero. Transcription of prospero is restricted by the additional requirement for Lozenge, a transcription factor expressed in the eye disc, and activation of the Notch receptor. The function of Notch appears to inhibit the transcription factor Su(H), which in the absence of Notch represses prospero transcription through direct binding to its enhancer.