Clonogenic assays. (A) Effect of ara-C (⋄, ×) and ara-C in combination with UCN-01 (♦, ^*) on the clonogenic survival of CFU-GM progenitor cells from normal bone marrow. (B) Effect of ara-C alone (○, ▵, □, ▿), UCN-01 alone (^*, +, ×, |), and ara-C in combination with UCN-01 (•, ▴, ▪, ▾) on the clonogenic survival of AML blasts. Symbols indicate the mean of 2 separate determinations from individual patients.