Relationship between uPA-, fibrinogen-, and ICAM-1–binding sites in α_Mβ₂.

The α_Mβ₂ cells were preincubated with increasing concentrations of Fg (A) or ICAM-1 (B) in DMEM/F-12/1 mM Mg²⁺, washed once and allowed to bind soluble (DFP-inactivated) Alexa 488–HMW-tc-uPA or the mixture was allowed to adhere to immobilized DIP–HMW-tc-uPA for 30 minutes at 37°C. Cell-bound uPA was detected by FACS, and the number of adherent cells was counted as described in “Materials and methods.” (C) α_Mβ₂ cells were preincubated with DIP–HMW-tc-uPA for 30 minutes at 37°C, washed once, and then seeded onto plates coated with 10 μg/mL ICAM-1. After 30 minutes at 37°C, plates were washed and adherent cells were counted.