IL1A and cardiac hypertrophy: In addition, the mRNA expression of two important cardiac hypertrophy genes (Myh7, Myosin heavy chain β and Nppb, encoding for the prohormone NT-proBNP) increased after MI (Fig. 4e,f), and this change was significantly attenuated in the heart of IL-1α KO mice, at day 3 (Nppb) and day 7 (Myh7, and, to a lesser extent Nppb).