CD338. also known as ABCG2 (ATP-binding cassette subfamily G member 2), is a transmembrane protein belonging to the ABC transporter superfamily. It functions as an efflux pump, expelling a wide range of substrates, including chemotherapeutic agents (e.g., mitoxantrone, topotecan), endogenous metabolites, and toxins, using ATP hydrolysis. Discovered in the late 1990s, ABCG2 gained attention for its role in multidrug resistance (MDR) in cancer, where its overexpression in tumor cells reduces intracellular drug accumulation, compromising chemotherapy efficacy. Additionally, ABCG2 is expressed in normal tissues (e.g., placenta, blood-brain barrier, liver, and intestines), contributing to tissue protection and xenobiotic excretion.
CD338 antibodies are critical tools for detecting ABCG2 expression in research and diagnostics. They are widely used in techniques like flow cytometry, immunohistochemistry, and Western blot to study ABCG2's distribution, function, and association with drug resistance. These antibodies also help identify cancer stem cells (CSCs), as ABCG2 is a marker of stem-like cells with self-renewal and therapy-resistant properties. In clinical settings, CD338 antibody-based assays may predict patient response to chemotherapy or guide targeted therapies. However, challenges remain, including ensuring antibody specificity due to structural similarities among ABC transporters. Ongoing research focuses on developing inhibitors to block ABCG2 activity, aiming to overcome MDR and improve treatment outcomes.