Serine protease which is capable of degrading a number of proteins such as casein, fibrinogen, kininogen, fibronectin and collagen type IV. Also cleaves L1CAM in response to increased neural activity. Induces neurite outgrowth and fasciculation of cultured hippocampal neurons. Plays a role in the formation and maturation of orphan and small synaptic boutons in the Schaffer-collateral pathway, regulates Schaffer-collateral long-term potentiation in the hippocampus and is required for memory acquisition and synaptic plasticity. Involved in skin desquamation and keratinocyte proliferation. Plays a role in the secondary phase of pathogenesis following spinal cord injury. Expressed at high levels in serum, ascites fluid and tumor cytosol of advanced stage ovarian cancer patients and may serve as a marker of ovarian cancer. Cleavage of amide substrates following the basic amino acids Arg or Lys at the P1 position, with a preference for Arg over Lys. Inhibited by a range of serine protease inhibitors including antipain, aprotinin, leupeptin, benzamidine and soybean trypsin inhibitor.