FN1 and infection: To determine the participation of integrin α5β1 in the fibronectin-mediated adherence of EAEC strain 042 to intestinal epithelial cells, prior to infection, we incubated T84 cells with fibronectin in the presence of two different antibodies: a polyclonal antibody against several epitopes of the integrin α5 molecule and a monoclonal antibody that only blocks the fibronectin-integrin α5β1 interaction site, the RGD site.