Accordingly, neutral endopeptidase (or neprilysin, NEP; fast cleaving the Pro10-Tyr11 and the Tyr11-Ile12 bonds) and angiotensin-converting enzyme (ACE; rapidly hydrolyzing the Tyr11-Ile12 bond) are the two key proteases expected to fast degrade NT-based radioligands entering the blood-stream in the narrow time-window they need to reach tumor site(s) [45,46,47,48]. The gene discussed is ACE; the disease is neoplasm.