Rap1 promotes myeloid cell integrin α4β1-ligand binding and conformational changes.

<p>(A) Representative histogram of soluble, fluorescently labeled VCAM-1/Fc bound to CD11b+ myeloid cells 3 min after treatment with (black line) or without (grey line) IL-1β. (B) Mean fluorescence intensity (MFI) of VCAM-1/Fc bound to WT, p110γ−/− and Rap1a−/− myeloid cells in the absence (basal) or presence of chemoattractants or the positive control stimulus Mn2+ (n = 3), *P<0.01, p110γ−/− or Rap1a−/− vs WT. (C) MFI of VCAM-1/Fc bound to pRapV12- and control-transfected WT and p110γ−/− myeloid cells (n = 3), *P<0.01, pRapV12 vs control. (D) MFI of VCAM-1/Fc bound to WT and Rap1a−/− myeloid cells transfected with p110γCAAX, pRapV12 or control plasmid or treated with Mn2+ (n = 3), *P<0.01, Rap1a−/− vs WT. (E) Representative histogram of HUTS21 antibody binding to unstimulated (grey line) or SDF-1α stimulated (black line) human CD11b+ myeloid cells. (F) MFI of HUTS21 binding to unstimulated or SDF-1α stimulated human myeloid cells in the presence of absence of 10 µM geranylgeranyltransferase inhibitor (GGTI-2147) or Mn2+ (n = 3), *P<0.01, +GGTI vs -GGTI.