Rocchi EKhodjakov AVolk E.LCHIH-HSIN YANGLitman TBates S.ESchneider E.2020-05-262020-05-2620000006-291Xhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-0034728768&doi=10.1006%2fbbrc.2000.2590&partnerID=40&md5=f0817f65c8b36ae0dcf53b56bb2d6e90https://scholars.lib.ntu.edu.tw/handle/123456789/495160The products of the ABC gene family can be generally classified as either full-transporters of half-transporters. Full-transporters are expressed in the plasma membrane, whereas half-transporters are usually found in intracellular membranes. Recently, an ABC half-transporter, the ABCG2 gene product Breast Cancer/Mitoxantrone Resistance Protein (BCRP/MXR), has been shown to cause mitoxantrone and topotecan resistance. The purpose of this study was to determine the expression and the intracellular localization of this protein in various drug-resistant cell lines. BCRP/MXR expression was determined by Western blot and immunohistochemistry. This protein is highly overexpressed in several drug-resistant cell lines and localizes predominantly to the plasma membrane, instead of to intracellular membranes as seen with all other known half-transporters. Therefore, BCRP/MXR is unique among the ABC half-transporters by being localized to the plasma membrane. (C) 2000 Academic Press.[SDGs]SDG3ABC transporter; mitoxantrone; topotecan; article; breast cancer; cell membrane; drug resistance; gene overexpression; human; human cell; immunoblotting; immunohistochemistry; intracellular membrane; priority journal; protein expression; protein localizationjournal article10.1006/bbrc.2000.2590107776782-s2.0-0034728768