Application Methods: Immunoprecipitation, Western Blotting
Background: Multi-drug resistance protein 2 (MRP2), also known as cMRP, cMOAT, and ABCC2, is an ATP binding cassette (ABC) transporter and part of the multi-drug resistance (MRP) family (1,2). The MRP proteins are membrane proteins that function as organic anion pumps involved in the cellular removal of cancer drugs (2). MRP2 is associated with resistance to a number of cancer drugs, such as cisplatin, etoposide, doxorubicin, and methotrexate (3-5). MRP2 is predominately expressed on the apical membranes in the liver (6-9) and kidney proximal tubules (10). It is responsible for the ATP-dependent secretion of bilirubin glucuronides and other organic anions from hepatocytes into the bile, a process important for the excretion of endogenous and xenobiotic substances. Loss of MRP2 activity is the cause of Dubin-Johnson syndrome, an autosomal recessive disorder characterized by defects in the secretion of anionic conjugates and the presence of melanin like pigments in hepatocytes (11-13).
Application Methods: Immunofluorescence (Immunocytochemistry), Immunoprecipitation, Western Blotting
Background: Translocator protein (TSPO) is an 18 kDa mitochondrial drug- and cholesterol-transporting protein involved in steroid hormone synthesis and mitochondrial homeostasis in a variety of cell types (1,2). Originally thought to play a role exclusively in steroid synthesis in steroidogenic cells, subsequent research studies have implicated TSPO in a variety of pathologies in a broad range of tissues including progression of breast cancer, neuroinflammation, and neurological disorders (1,3-5). TSPO was first identified by its ability to bind benzodiazepines in peripheral tissues and glial cells, hence its alternate name Peripheral Benzodiazepine Receptor (PBR).TSPO has been shown to modulate an array of cellular functions; it is critical for steroidogenesis, modulates mitochondrial function and metabolism, and plays a role in both cell proliferation and apoptosis (6-8). TSPO is found in the outer mitochondrial membrane where it coordinates with Steroidogenic Acute Regulatory Factor (StAR) to transport cholesterol into the mitochondria and is critical for steroidogenesis and tumor progression (9,10). This is illustrated by studies that show the non-aggressive, hormone-dependent cell line, MCF7, expresses low levels of TSPO whereas the more aggressive, metastatic, and hormone-independent cell line, MDA-MB-231, expresses high levels of TSPO (10). This study, and others, suggest that TSPO may be an important regulator of hormone-dependent tumor progression. Numerous investigations have concluded that due to its high affinity for pharmacological compounds and up-regulation in disease, TSPO is an attractive target for diagnosis and treatment of tumor progression, neuroinflammation, neurodegeneration, and neurological/psychiatric disorders (11-15).