TLR4 and heart failure: Incubation with 100 μM of isoproterenol (ISO) for 6 days resulted in a dramatic induction of heart failure markers (Nppa, Nppb and Tlr4) (Figure 5A) and a significant reduction in the RBFox2 protein (Figure 5B) in cultured NRCMs, indicating cardiomyocyte dysfunction after a prolonged ISO treatment.