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Semin Cancer Biol. 1997 Jun;8(3):161-70.

The physiological function of drug-transporting P-glycoproteins.

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Division of Experimental Therapy, The Netherlands Cancer Institute, Amsterdam, The Netherlands.


The mammalian drug-transporting or mdr1-type P-glycoproteins can extrude a range of structurally diverse, toxic xenobiotic compounds from cells. Our analysis of knockout mice lacking one or both of the mdr1-type P-glycoproteins indicates that a major function of these proteins is the protection of organisms against many of the toxic xenobiotics to which they can potentially be exposed in nature. P-glycoprotein confers protection by limiting the uptake of compounds from the gastrointestinal tract, and by stimulating excretion of compounds in the liver, kidney, and intestine. Moreover, P-glycoprotein in the blood-brain barrier and other blood-tissue barriers protects sensitive organs from exposure to toxic compounds that may have entered the bloodstream. Although we cannot exclude additional physiological functions for mdr1-type P-glycoproteins, these are not vital, since the mdr1-deficient mice are viable and fertile, and do not display obvious phenotypic abnormalities other than hypersensitivity to drugs.

[Indexed for MEDLINE]

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