Class IA PI3K(p110α), the cardiac-protective isoform of PI3K, acts as a master effector of insulin-like growth factor 1 (IGF-1), upstream activator of PI3K in the heart, which is known to be responsible for exercise induced myocardial hypertrophy (10) and even for an increased cardiac contractility (11, 12). Here, IGF1 is linked to cardiac hypertrophy.