The microphthalmia-associated transcription factor (Mitf) is critical for mast cell development
based on the severe mast cell deficiency seen in Mitf mutant mice. Mitf also is important for
the development of melanocytes, osteoclasts, and retinal pigment epithelium. The lineage-
restricted phenotypes of Mitfmutations correlate with tissue-restricted expression of Mitf, a
feature due in part to the presence of several distinct Mitf isoforms. We report the
identification and characterization of a novel mast cell isoform, Mitf-mc. This isoform arises …