This gene is a member of the superfamily of ATP-binding cassette (ABC) transporters and the encoded protein contains two ATP-binding domains and 12 transmembrane regions. ABC proteins transport various molecules across extra- and intracellular membranes. ABC genes are divided into seven distinct subfamilies: ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, and White. This gene is a member of the MRP subfamily which is involved in multi-drug resistance. This gene and another subfamily member are arranged head-to-tail on chromosome 16q12.1. Increased expression of this gene is associated with breast cancer. [provided by RefSeq, Jul 2008]