Hypothetical model for MN1 function in myeloid progenitor cells. MN1 affects both differentiation and proliferation of myeloid progenitors. In this model, MN1 binds to the coactivator p300/CBP, which is (1) recruited to RAR/RXR target genes whose transcriptional repression inhibits differentiation. P300/CBP can also recruit MN1 to as-yet-unknown transcription factors (X) that (2) regulate genes affecting cell growth either by transcriptional activation (A) or repression (B).