This gene encodes a member of the Myc superfamily of basic helix-loop-helix leucine zipper transcriptional regulators. The encoded protein forms a heterodimer with the cofactor MAX which binds specific E-box DNA motifs in the promoters of target genes and regulates their transcription. Disruption of the MAX-MXD3 complex is associated with uncontrolled cell proliferation and tumorigenesis. Transcript variants of this gene encoding different isoforms have been described.[provided by RefSeq, Dec 2008].