Breast Cancer Resistance Protein, known as BCRP or ABCG2, is a member of the ATP-binding cassette (ABC) transporter family. It functions as a drug efflux pump, actively transporting a wide range of substrates, including chemotherapeutic agents, out of cells. BCRP is expressed in various tissues, including the placenta, liver, intestine, and blood-brain barrier, playing a crucial role in protecting tissues from xenobiotics and toxins.