Breast Cancer Resistance Protein (BCRP) is an efflux transporter responsible for causing
multidrug resistance (MDR). It is known to expel many potent antineoplastic drugs, owing to
its efflux function. Efflux of chemotherapeutics because of BCRP develops resistance to many
drugs, leading to failure in cancer treatment. BCRP plays an important role in physiology by protecting
the organism from xenobiotics and other toxins. It is a half-transporter affiliated to the ATP-
binding cassette (ABC) superfamily of transporters, encoded by the gene ABCG2 and functions
in response to adenosine triphosphate (ATP). Regulation of BCRP expression is critically controlled
at molecular levels, which help in maintaining the balance of xenobiotics and nutrients inside
the body. Expression of BCRP can be found in brain, liver, lung cancers and acute myeloid
leukemia (AML). Moreover, it is also expressed at high levels in stem cells and many cell lines.
This frequent expression of BCRP has an impact on the treatment procedures and, if not scrutinized,
may lead to the failure of many cancer therapies.