Nitrosourea CompoundsCarmustineSemustineLomustineNimustineO(6)-Methylguanine-DNA MethyltransferaseAntineoplastic Agents, AlkylatingMethylnitrosoureaEthylnitrosoureaMustard CompoundsAlkylating AgentsLeukemia L1210GuanineMethyltransferasesBrain NeoplasmsMisonidazoleEthyl ChlorideGliomaDacarbazineCyclohexylaminesCell SurvivalAntineoplastic AgentsNeoplasms, ExperimentalNitroimidazolesDrug ResistanceStreptozocinDose-Response Relationship, DrugEflornithineDrug SynergismGlutathione ReductaseCyanatesCyclohexanesNeoplasm TransplantationAlkylationOrnithineEpendymomaDNA RepairDrug Screening Assays, AntitumorSister Chromatid ExchangeAziridinesMethionine SulfoximineTumor Cells, CulturedStructure-Activity RelationshipNitroso CompoundsButhionine SulfoximineMechlorethamineDNA, Neoplasm