Angiotensin-(1-7) receptor Mas is an essential modulator of extracellular matrix protein expression in the heart

► We evaluated the role of Mas in extracellular matrix protein expression in hearts. ► Expression of collagens I, and III and fibronectin is higher in neonatal and adult Mas−/− hearts. ► These changes may contribute to the decreased heart function observed in Mas−/− mice.