Multidrug transporters, such as MFSD2B, are membrane proteins that expel a wide spectrum of cytotoxic compounds from the cell and render cells resistant to multiple drugs. Major Facilitator Superfamily (MFS) members are capable of transporting various substrates such as sugars, polyols, drugs, neurotransmitters, amino acids, peptides, and inorganic anions, although most members are substrate-specific. MFSD2B is closely related to MFSD2A, which is expressed in many tissues and is highly induced in liver and brown adipose tissue (BAT) during fasting, playing a major role in the induction of MFSD2A expression during adaptive thermogenesis. Unlike MFSD2A, MFSD2B is expressed in few tissues and at relatively low levels, and is not induced during fasting, suggesting that MFSD2B may play other roles.