PGP and cancer: Gewering investigated P-glycoprotein (Pgp),30 a prototypical ATP-binding cassette (ABC) transporterinvolvedin cancer drug resistance and a central mediator of the bioavailabilityand pharmacokinetics of many drugs.31 Bycovalently attaching a cyclic substrate to select sites on the sequenceof Pgp, the authors used cryoEM to determine multiple complex structuresin inward- and outward-facing states.