ia [57]. Moreover, under hypoxic conditions human pulmonary artery smooth muscle cells upregulated both (arms of the RAS) ACE and ACE2 mRNA and protein expression, and ACE2 was subsequently downregulated by (ACE-derived) Ang II through an AT1R-mediated process [58]. Similarly, both ACE and ACE2 expression were increased in vascular endothelium and smooth muscle of