Another way that mast cells might drive arthritis was proposed to be through the release of tryptase/heparin complexes, which were shown to induce the expression of the neutrophil chemoattractants, CXCL1, CXCL5, and CXCL8, in cultured fibroblast-like synoviocytes (49). The gene discussed is CXCL1; the disease is arthritic joint disease.