DNA sequence-specific proteins called transcription factors found in all multicellular organisms control the expression of genes and are involved in the regulation of the cell cycle. Myb oncoproteins are transcription factors with a distinct DNA binding domain lacking zinc fingers or a basic region. Found originally in the avian myeloblastosis virus (v-Myb), then in the genome of chickens (c-Myb), the DNA binding domain of Myb occurs in regulatory proteins from mammals including humans, plants, flies, Dictyostelium, and yeast. Myb proteins show a preference for the AACGTT, AACnGTT and the [GRAPHICS] motifs with AAC (or its complementary GTT) as the core recognition site. Our searches through a dictionary of DNA recognition sequences of vertebrate transcription factors for Myb sites suggests that a subset of regulatory sequences of defined genes that are targets of the transcription factors XBP, ATF, LRF-1, GR, NF-AT, HNF-1, GATA-1, H1P1, alpha-CP-1, AP-3, RF-X, the nuclear matrix protein SATB1, and the ETS proteins PEA3, E74A, and GABPalpha share the Myb binding site and might thus 'crosstalk' with Myb on selected genomic targets.

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