Pro-oxidative signaling by shared epitope (SE)-expressing peptides. (a,b) The potency of adenosine-induced anti-oxidative signaling was determined in human M1 fibroblasts, which had been pre-incubated overnight with 50 μg/ml of different 15 mer (a) or 5 mer (b) peptides. *p < 0.05. (c) Dose-response analysis of soluble peptide-mediated pro-oxidative effect. AA, amino acid; IC50, half inhibitory concentration.