Interferon regulatory factor 5 (IRF5), is a multifunctional regulator of immune responses, with a critical role in controlling pro-inflammatory responses of macrophages. IRF5 contributes to the pathogenesis of several inflammatory and autoimmune diseases. Given the importance of IRF5 function in physiology and disease, IRF5 represents a therapeutic target. However, the mechanisms regulating IRF5 activation and the kinases responsible for its phosphorylation in vivo have been unclear. The p...