A 170-kDa transmembrane glycoprotein from the superfamily of ATP-BINDING CASSETTE TRANSPORTERS. It serves as an ATP-dependent efflux pump for a variety of chemicals, including many ANTINEOPLASTIC AGENTS. Overexpression of this glycoprotein is associated with multidrug resistance (see DRUG RESISTANCE, MULTIPLE).

Genes for MEMBRANE TRANSPORT PROTEINS that confer resistance to toxic compounds. Several superfamilies of these multidrug export proteins are known and found in both prokaryotes and eukaryotes.

Simultaneous resistance to several structurally and functionally distinct drugs.

A subfamily of transmembrane proteins from the superfamily of ATP-BINDING CASSETTE TRANSPORTERS that are closely related in sequence to P-GLYCOPROTEIN. When overexpressed, they function as ATP-dependent efflux pumps able to extrude lipophilic drugs, especially ANTINEOPLASTIC AGENTS, from cells causing multidrug resistance (DRUG RESISTANCE, MULTIPLE). Although P-Glycoproteins share functional similarities to MULTIDRUG RESISTANCE-ASSOCIATED PROTEINS they are two distinct subclasses of ATP-BINDING CASSETTE TRANSPORTERS, and have little sequence homology.

A fluorescent probe with low toxicity which is a potent substrate for P-glycoprotein and the bacterial multidrug efflux transporter. It is used to assess mitochondrial bioenergetics in living cells and to measure the efflux activity of P-glycoprotein in both normal and malignant cells. (Leukemia 1997;11(7):1124-30)

Diminished or failed response of an organism, disease or tissue to the intended effectiveness of a chemical or drug. It should be differentiated from DRUG TOLERANCE which is the progressive diminution of the susceptibility of a human or animal to the effects of a drug, as a result of continued administration.

A sequence-related subfamily of ATP-BINDING CASSETTE TRANSPORTERS that actively transport organic substrates. Although considered organic anion transporters, a subset of proteins in this family have also been shown to convey drug resistance to neutral organic drugs. Their cellular function may have clinical significance for CHEMOTHERAPY in that they transport a variety of ANTINEOPLASTIC AGENTS. Overexpression of proteins in this class by NEOPLASMS is considered a possible mechanism in the development of multidrug resistance (DRUG RESISTANCE, MULTIPLE). Although similar in function to P-GLYCOPROTEINS, the proteins in this class share little sequence homology to the p-glycoprotein family of proteins.

Resistance or diminished response of a neoplasm to an antineoplastic agent in humans, animals, or cell or tissue cultures.

A family of MEMBRANE TRANSPORT PROTEINS that require ATP hydrolysis for the transport of substrates across membranes. The protein family derives its name from the ATP-binding domain found on the protein.

Antineoplastic antibiotic obtained from Streptomyces peucetius. It is a hydroxy derivative of DAUNORUBICIN.

A calcium channel blocker that is a class IV anti-arrhythmia agent.

This line KB is now known to be a subline of the ubiquitous KERATIN-forming tumor cell line HeLa. It was originally thought to be derived from an epidermal carcinoma of the mouth, but was subsequently found, based on isoenzyme analysis, HeLa marker chromosomes, and DNA fingerprinting, to have been established via contamination by HELA CELLS. The cells are positive for keratin by immunoperoxidase staining. KB cells have been reported to contain human papillomavirus18 (HPV-18) sequences.

A very toxic anthracycline aminoglycoside antineoplastic isolated from Streptomyces peucetius and others, used in treatment of LEUKEMIA and other NEOPLASMS.

Large cytoplasmic ribonucleoprotein particles that have an eight-fold symmetry with a central pore and petal-like structure giving the appearance of an octagonal dome. (The Dictionary of Cell Biology, Lackie and Dow, 2nd ed.)

Antitumor alkaloid isolated from Vinca rosea. (Merck, 11th ed.)