Neutral endopeptidase is expressed on benign prostate epithelial cells but dramatically downregulated in metastatic human PC (Papandreou et al, 1998), and contributes to the transition of hormonally regulated androgen-dependent to independent PC (Papandreou et al, 1998) both via enzymatic activity and by nonenzymatic signalling interactions (Papandreou et al, 1998; Sumitomo et al, 2000). The gene discussed is MME; the disease is pachyonychia congenita.