The subcellular localization of P210^BCR-ABL is independent of tyrosine kinase activity.

(A) NIH3T3 cells were transduced with pK1, P210^BCR-ABL, or K1176R retroviral vectors and selected with puromycin to determine if F-actin colocalization is also independent of tyrosine kinase activity. Cells were attached to fibronectin-coated coverslips overnight in the presence or absence of 10 μM STI571 as indicated. (B) 32D cells expressing P210^BCR-ABL or control pK1 (data not shown) were treated with 10 μM STI571 or an equal volume of PBS overnight in the presence of WEHI media containing IL-3. Cells were allowed to bind fibronectin-coated coverslips for 15 minutes prior to fixing and staining cells according to the same protocol used to prepare 32D cells for adhesion assays. 32D and NIH3T3 cells were imaged using confocal microscopy. Colocalization of BCR-ABL with F-actin appears yellow or orange when BCR-ABL (red) and actin (green) are merged. All cells were stained with DAPI to visualize the nucleus (blue). Positive nuclear staining observed in pK1-transduced control NIH3T3 cells is likely due to endogenous c-abl expression. Total magnification, × 120.