Effect of imatinib mesylate on G-CSF–induced granulocytic differentiation in 32D_Bcr-Abl cells expressing an imatinib mesylate-resistant mutant.

Imatinib mesylate fails to restore G-CSF–induced granulocytic differentiation in 32D_Bcr-Abl cells expressing an imatinib mesylate-resistant mutant. (A) The 32D_Bcr-Ablwtand 32D_{Bcr-AblThr315Iso} cells established by retroviral infection were either left untreated or incubated with 1 or 10 μM imatinib mesylate for 2 hours prior to lysis. Western blot analysis was performed with antibodies to phosphotyrosines and Abl. (B) The 32Dcl3, 32D_Bcr-Ablwt, and 32D_{Bcr-AblThr315Iso} cells were grown in media containing G-CSF. Imatinib mesylate was added at a concentration of 1 μM as indicated. Morphological differentiation of cytospun cells was determined at day 10 by May-Gruenwald-Giemsa staining (original magnification, × 400). Cells grown in the presence of IL-3 are shown as a control.