Dipeptidyl peptidase I activates neutrophil-derived serine proteases and regulates the development of acute experimental arthritis
J. Clin. Invest. April M. Adkison, et al. 109:363 doi:10.1172/JCI13462 [Go to this article.]

Figure 1
Analysis of PMN-derived serine proteases in DPPI^–/– mice. NE (a) and CG (b) protein expression in DPPI^–/– bone marrow lysates. β-actin served as control for protein content. Note the markedly reduced level of immunoreactive CG in DPPI^–/– bone marrow lysate compared with WT. (c) S1 nuclease protection assay revealed equivalent levels of CG mRNA in DPPI^–/– and WT bone marrow lysate. β₂ microglobulin (β₂m) served as control for RNA loading. (d) DPPI^–/– bone marrow cells and NE^–/– bone marrow cells have equivalent residual levels of NE activity. (e) Both DPPI^–/– and CG^–/– bone marrow cells have no detectable hydrolysis of the CG-specific peptide substrate. (f) Conversion of the PR3 substrate by DPPI^–/– bone marrow cell lysate was reduced by 80% compared with WT. Relative enzyme activity was measured at OD₄₀₅ per 10⁵ bone marrow cells and values represent mean activity ± SEM of at least three animals.