HIF1A and cardiac hypertrophy: Thorough pathway analysis showed that ET-1 stimulation of hiPSC-CMs cultured in maturation medium significantly activated the cardiac hypertrophy pathway, as well as additional signaling pathways related to hypertrophic response, including calcium, actin cytoskeleton, ILK, HIF1a, G-protein-coupled receptor, HMGB1, and IL-6 signaling, amongst others (Figure 6E).