REN and carcinoma: To verify the results of prediction analysis, we transiently expressed renin isoforms with mutations located in the leader peptide (p.W10R, p.L16del, p.L16R, p.W17R and p.C20R) and in the pro-segment (p.M39K and p.E348K) in Calu-6 cells, a human carcinoma-derived cell line expressing human renin endogenously at low levels (Lang et al., 1996).