IRAK1 and atherosclerosis: Two signaling pathways are likely involved in IRAK1-associated VSMC proliferation: (a) the IL-1/IL-18 inflammatory pathway, in which activation of IRAK1 induces production of inflammatory cytokines such as IL-1 and IL-18 which, in turn, provokes VSMC proliferation during atherosclerosis progression [59]; and (b) the kinase pathway, in which IRAK1 facilitates VSMC proliferation and neointimal hyperplasia by activating protein kinase C (PKC) and extracellular signal regulated kinase (ERK) [60].