Figure 4.

Paxillin association with α₄ facilitates integrin anchorage to the cytoskeletal matrix. (A) Detergent removal of nonligated wt α₄ monitored by FACS. Jurkat cells were reacted for 30 min at 4°C with FITC-conjugated anti-α₄β₁ mAb (HP1/2) or isotype-matched control (dotted line). Cells were then incubated at RT in detergent-free buffer (black, −NP-40) or in buffer containing 0.05% NP-40 (gray, +NP-40). The fraction of α₄-bound mAb remaining after detergent treatment assessed by flow cytometry is shown relative to originally bound α₄ mAb. (B) The fraction of mAb-bound wt or α₄(Y991A) resistant to detergent-induced removal was compared before (white bars) and after ligation of the mAb by secondary antibody (black bars). Results are a mean of three independent experiments. Error bars represent SD.