Imatinib decreases the formation and activity of OCs. CD14⁺ cells from healthy donors were used to establish OC assays to examine the effect of imatinib on bone resorption and the formation of TRAP⁺ cells. The mean number of TRAP⁺ cells (A) was significantly reduced in the presence of 3.0 μM imatinib, whereas resorption (B) and lacunae number (C) were affected at 0.3 μM imatinib. Results are representative of 3 individual experiments using different donors. *P < .05. Error bars represent the standard error of the mean (SEM).