The substrates of macrophage MMP12 were investigated using TAILS by incubating murine MMP12 with secretomes from Mmp12−/− murine embryonic fibroblasts (MEFs), murine macrophage cell line RAW264.7 secretomes and also by comparing WT and Mmp12−/− peritoneal macrophages from a peritonitis model using thioglycollate stimulation for 4 days [71]. This evidence concerns the gene MMP12 and peritonitis.