Interestingly, IGFBP‐3, a protein chaperone of IGFs, and PDGF‐AA, a growth factor involved in the regulation of mesenchymal cell proliferation and tumour progression, are two putative substrates of KLKs in a model of ovarian cancer cells overexpressing KLK4‐7 (Matsumura et al., 2005; Prassas et al., 2015; Shahinian et al., 2014), which may explain their decrease in expression after KLK4 treatment. The gene discussed is KLK4; the disease is ovarian cancer.