Effects of imatinib on activities of AKT kinase in CML samples. AKT kinase assays were performed on CML CD34⁺ cells cultured with or without imatinib (1 and 5 μM) for 16 hours in medium containing low concentrations of GF. AKT was immunoprecipitated, and in vitro kinase assays were performed with the use of a GSK-3 fusion protein as substrate followed by Western blotting with an anti–phospho–GSK-3α/β antibody. The difference between imatinib treated cells and untreated cells was not significant (P = .4 for 1 μM imatinib; P = .18 for 5 μM imatinib). (A) Representative results for 2 CP and 2 AP patients. (B) Pooled results for treated cells relative to controls is shown (mean ± SEM, n = 6).