Treatment of Bcr-Abl⁺ BaF3p185 cells with antibodies to the fibronectin receptor chains leads to a significant reduction of the fibronectin-mediated antiapoptotic effect.

Bcr-Abl⁺ BaF3 cells with or without STI571/IL-3 were cultured in the absence (■) or presence of anti-α5/β1 (░) or anti-α4/β1 (■) integrin antibodies. Cells were then plated on immobilized fibronectin or polylysin and cultured overnight at 37°C. All cells (nonadherent and adherent cells) were then irradiated with 0 Gy or 50 Gy and grown for an additional 8 hours. The percentage of apoptotic cells was determined by using Annexin V-FITC staining. Values reflect the mean ± SEM of 3 independent examinations.