KB CellsCell LineCell Line, TumorTumor Cells, CulturedDrug ResistanceCell Line, TransformedDrug Resistance, NeoplasmTransfectionHybrid CellsP-GlycoproteinDrug Resistance, MultipleCell DivisionCricetinaeRNA, MessengerAntineoplastic AgentsMolecular Sequence DataBase SequenceCell SurvivalClone CellsMice, NudeFolate Receptors, GPI-AnchoredDrug Screening Assays, AntitumorDoxorubicinMutationApoptosisCell Transformation, NeoplasticCricetulus