It should be mentioned, that two other members of the type II transmembrane serine protease family, hepsin and TMPRSS13, which have previously been reported as being able to cleave and activate pro-HGF in vitro [30–32], were readily detectable by western blot analysis in a variety of breast cancer cells lines (unpublished data), which included the SUM149 and SUM190 lines used in this study. The gene discussed is TMPRSS13; the disease is breast cancer.