ACE2 is a new component of the RAS that was discovered in 2000 [2, 3] . It is the first known human homologue of ACE but differs from ACE in substrate specificity. Although ACE2 was first shown to cleave Ang I to Ang (1-9) [3] , which can be converted by ACE into the heptapeptide Ang-(1-7), another study showed that ACE2 hydrolysis of Ang II into Ang-(1-7) has a much higher efficiency (∼400-fold) than that for Ang I to Ang (1-9) [4] .