In Lewis rat model of arthritis, EPCs are recruited to inflamed synovium and form new vessels, which was blocked by specific plasma kallikrein inhibitor; Bradykinin stimulates transendothelial migration of EPCs by selectively upregulating expression of homing receptor C-X-C motif receptor 4 (CXCR4) [51]. Here, KLK4 is linked to arthritic joint disease.