In addition to its described role in tumour cell invasion and metastasis, the serine protease PMN-E may, similar as has been suggested for uPA for human ovarian carcinoma cells (Fischer et al, 1998) and breast cancer cells (Foekens et al, 1995), provoke cell proliferation via enzymatic activation of several growth factor (receptor) pathways. The gene discussed is PLAU; the disease is breast carcinoma.