Effect of AG957 on CML (▪) and normal (○) CD34⁺-derived CFU-Mix (A), BFU-E (B), and CFU-GM (C). Each data point represents the mean (±SEM) percentage of inhibition from separate experiments using 10 CML and 6 normal samples. For CML, control colonies per 1 × 10³ CD34⁺ cells ranged from 2 to 7 for CFU-Mix, 39 to 80 for BFU-E, and 31 to 180 for CFU-GM. For normal samples, control colonies 1 × 10³CD34⁺ cells ranged from 4 to 8 for CFU-Mix, 24 to 96 for BFU-E, and 40 to 64 for CFU-GM. When compared with control cultures (Wilcoxon signed-rank test), the inhibitory effect of AG957 on CML progenitors was statistically significant at the dose of 1 μmol/L for CFU-Mix (P = .04) and BFU-E (P = .01) and of 5 μmol/L for CFU-GM (P = .04). The inhibitory effect of AG957 on normal progenitors was statistically significant at the dose of 5 μmol/L for CFU-Mix (P = .02), and BFU-E (P = .04) and 10 μmol/L for CFU-GM (P = .03).