pretreatment of 9l cells for 48 hr with 0.2 microm 6-thioguanine potentiated the cytotoxicity of 1,3-bis ( 2-chloroethyl ) -1-nitrosourea ( bcnu ) by 50 % with a dose enhancement ratio of 1.5 , and caused a 30 % increase in the number of bcnu-induced sister chromatid exchanges ( sces ) and a 50 % increase in dna crosslinks formed , compared to treatment with bcnu alone .
C0007634
cells
C0037211
sister chromatid