KLK4 and ovarian cancer: The importance of the specific mix of kallikreins present and their relative abundance on the activome is underscored by the drastic difference within our clones, and with other published reports such as the findings of Prezas et al. [57] who have shown that the OV-MZ-6 ovarian cancer cell line engineered to co-express KLK4/5/6/7 displayed an increased tumourigenicity.