Effects of fibronectin binding in BaF3 cells expressing kinase active Bcr-Abl.

(A) Expression of β1, α4, and α5 integrin chains in wt andbcr-abl–transfected BaF3 cells were analyzed by flow cytometry. Bcr-Abl⁺ and Bcr-Abl⁻ BaF3 cells were stained with an isotype control antibody (filled curves) or with monoclonal antibodies directed against β1, α4, and α5 integrin subunits (solid lines). (B) Adhesion of Bcr-Abl⁺ and Bcr-Abl⁻ cells to fibronectin. Wild-type BaF3 cells supplemented with IL-3 and Bcr-Abl⁺ BaF3p185 cells in the absence or presence of STI571/IL-3 were cultured for 17 hours on immobilized fibronectin. Numbers of cells in suspension and adherent cells were determined by using a hemocytometer. Values reflect the mean ± SEM of 3 independent examinations. (C) Percentage of S-phase in adherent cells grown on immobilized fibronectin. Cell cycle analysis of adherent Bcr-Abl⁺ cells with or without STI571+IL-3 and wtBaF3 cells grown on fibronectin was determined by propidium iodide staining and FACScan. Values reflect the mean ± SEM of 3 independent examinations. (D) Differences in actin staining of Bcr-Abl–transformed BaF3 cells with or without STI571/IL-3 grown on fibronectin or polylysin. Adherent cells were fixed and stained for F-actin by using rhodamine-labeled phalloidin.