Efflux pump; part of the gene cluster that mediates the biosynthesis of the secondary metabolite ustiloxin B, an antimitotic tetrapeptide (PubMed:24841822, PubMed:27166860, PubMed:26703898). Probably involved in self-resistance through the export of ustiloxin B (PubMed:24841822). Mycotoxin biosynthesis. Decreases the production of ustiloxin B (PubMed:24841822, PubMed:26703898). Belongs to the major facilitator superfamily.