PDI interacts with β3 integrins on cell surfaces. (A) Interaction of PDI with P-selectin, α_IIbβ₃, or α_Vβ₃. Histograms show fluorescence intensity of Alexa 488–labeled recombinant PDI interacting with CHO cells expressing either P-selectin (red), α_IIbβ₃ (green), or α_Vβ₃ (blue). CHO cells were pretreated for 10 minutes in PBS with or without Mn²⁺ and incubated with PDI labeled with Alexa 488. (B) CHO cells expressing either α_IIbβ₃ (left) or α_Vβ₃ (right) were incubated with Alexa 488–labeled PDI in the presence of Mn⁺² (green) or EDTA (blue). The interaction of PDI with CHO cells expressing P-selectin (red) is shown as control.