Correlation of the cytotoxicity of araC and the cell content of es nucleoside transporters. The data of Fig 5 are plotted as the differential cell kill by araC (the difference between cell survival (a) in the presence of the 1 μmol/L NBMPR/araC combination and (b) in the presence of lower, graded NBMPR concentrations with araC) versus the es-specific 5-(Sx8)-F fluorescence for each NBMPR-treated subpopulation of cells. The hyperbolic function fitted to the data shows a close correlation of cytotoxicity and es site content. (A) OCI/AML-2 cells; (B) blasts from AML patient H.M.; (C) CEM cells; (D) blasts from ALL patient T.Z.