MAS1 and lung disorder: The importance of ACE-2 does not only lie in its role as a viral entry receptor, but also as a lung protective enzyme leading to a further complicated role in lung disease.10 The enzyme ACE-2 produces the peptide product Ang1-7 that exerts its action on the receptor Mas oncogene in what is known as ACE-2/Ang1-7/Mas axis.