Murine synovial fibroblasts have impaired integrin-mediated signaling on citrullinated fibronectin. Synovial fibroblasts were allowed to adhere for 3 hours on plates coated with BSA as a negative control, fibronectin (FN), citrullinated fibronectin (FNC), or fibronectin incubated with heat-inactivated peptidyl arginine deiminase (FNHI). Cell lysates were subjected to SDS-PAGE followed by western blotting for total focal adhesion kinase (FAK), FAK phosphorylated at Y397, total paxillin, and paxillin phosphorylated at Y118. (A) Blots shown are representative of three experiments. (B) Western blots were quantified by densitometry. The amount of phosphorylated protein was normalized to total protein and this value was normalized to the overall intensity of the blots. The average and standard error are shown for three experiments. *P < 0.05, **P < 0.01, ***P < 0.005.