Although MyD88 was originally identified as a myeloid-differentiation marker (13), MyD88 is typically known to play an essentialrole in the innate immune response (14).Generation of MyD88-deficient mice has revealed new and important insights into thefunction of MyD88 in cardiac remodeling of several cardiomyopathy diseases.MyD88-knockout mice are protected from experimental autoimmune myocarditis (15), Coxsackievirus B3-induced myocarditis (16), and endotoxin-induced cardiomyopathy (17, 18, 19). The gene discussed is MYD88; the disease is myocarditis.