The membrane-associated protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters ABC proteins transport various molecules across extra- and intra-cellular membranes ABC genes are divided into seven distinct subfamilies (ABC1 MDR TAP MRP ALD OABP GCN20 White) This protein is a member of the MDR TAP subfamily Members of the MDR TAP subfamily are involved in multidrug resistance The protein encoded by this gene is an ATP-dependent drug efflux pump for xenobiotic compounds with broad substrate specificity It is responsible for decreased drug accumulation in multidrug-resistant cells and often mediates the development of resistance to anticancer drugs This protein also functions as a transporter in the blood-brain barrier Mutations in this gene are associated with colchicine resistance and Inflammatory bowel disease 13 Alternative splicing and the use of alternative promoters results in multiple transcript variants