Correlation of es nucleoside transporter expression and the sensitivity of cells to araC. Shown is a plot of data obtained with leukemia cells from AML patient H.M. (▪), ALL patient T.Z. (♦), and acute leukemia cell lines OCI/AML-2 (▴) and CEM (•). Chemosensitivity is shown as the log IC₅₀ for araC in a 72-hour MTT assay (Fig 1), and es expression as the log B_max for 5-(Sx8)-F binding, determined from flow cytometric measurements (Fig 2). P = .047; r = .95.