Pleiotropic ABC efflux transporter involved in the protection of the cells against a wide range of toxic compounds. Expression is strongly increased in the presence of cycloheximide, imazalil, itraconazole, hygromycin, and 4-nitroquinoline oxide (4-NQO). Belongs to the ABC transporter superfamily. ABCB family. Multidrug resistance exporter (TC 3.A.1.201) subfamily.