Because KLK7 has been proposed to act as a proliferative factor in many cancer types (Kryza et al., 2016; Walker et al., 2014), we next investigated the effect of KLK7 on mitogen‐activated protein kinase (MAP kinase) (ERK1/2) phosphorylation, an upstream kinase in the proliferation pathways. Here, MAPK3 is linked to cancer.