Adherence through protein receptors on HEp-2 cells. (A) Adhesion of E. coli to surface-modified HEp-2 cells. HEp-2 cells were pre-incubated with medium alone, pronase (50 and 500 μg/ml), and phospholipase A2 (200 μg/ml), respectively, prior to the adhesion assay. (B) Adhesion of E. coli to HEp-2 cells with pre-treatment of monoclonal antibodies (mAb) against α2, β1, and α2β1 integrins. (C) Adhesion of E. coli to HEp-2 cells with pre-treatment of polyclonal antibodies (pAb) against α2 and β1 integrins. (D) Adhesion of E. coli to C2C12 myoblasts and HUVECs. Data represent means of five experiments with triplicate samples in each experiment. *P < 0.05, **P < 0.01, and ***P < 0.001.