Figure 6

u-PA^-/- mice show increased expression of the matrix metalloproteinase-mediated neoepitope, DIPEN, during antigen-induced arthritis. (a) Representative DIPEN staining in knee joints from C57BL/6 and u-PA^-/- mice at week 1 after intra-articular (i.a.) injection. (b) Quantification of DIPEN staining at weeks 1, 2, and 6 after i.a. injection. Results are expressed as the mean ± standard error of the mean (five mice per group). *P = 0.03, **P = 0.003, C57BL/6 versus u-PA^-/- mice; P = 0.003, C57BL/6 over time; P = 0.03, u-PA^-/- over time. mBSA, methylated bovine serum albumin; u-PA^-/-, urokinase-type plasminogen activator gene-deficient.