The DNA replication-related element-binding factor (DREF) is a transcriptional regulator of the Drosophila myb gene.

Drosophila melanogaster possesses a single gene, Dm myb, that is closely related to the vertebrate proto-oncogene c-Myb, and its other family members (A-Myb and B-Myb), all of which encode transcription factors. Dm myb is expressed in all proliferating cells throughout development, and previous studies demonstrate that Dm myb promotes both S-phase and M-phase in proliferating cells, while preserving diploidy by suppressing endoreduplication. We have initiated a characterization of the mechanisms that regulate Dm myb expression, and we report here that the transcriptional activator DREF (the DNA replication-related element binding factor) activates Dm myb transcription via two binding sites located in the 5' flanking region; that the Dm myb promoter lacks a prototypical TATA box sequence and instead appears to use an initiator/downstream promoter element (Inr/DPE) type promoter; and that Dm myb expression is regulated at the translational as well as transcriptional level.