FMO5 and systemic sclerosis: Since inappropriate NADPH oxidase activation seems to play a fundamental role in determining fibrosis in SSc (1, 4, 8, 9), and FPRs are able to activate NADPH oxidase, both in leukocytes (14) and epithelial cells (13), we sought to investigate whether FPRs could be involved in ROS generation in fibroblasts derived from normal and SSc subjects, through the interaction with the urokinase (uPA)/urokinase receptor (uPAR) system.