Kallikrein 8 (hK8), also known as neuropsin, brain serine protease 1 (BSP1), tumor associated differentially expressed gene 14 (TADG14), PRSS19, HNP and ovasin, is a trypsin like serine protease. Originally described from mouse brain, KLK8 was implicated in neural plasticity and learning. Kallikrein 8 is thought to be involved in neurite outgrowth and fasciculation during nervous system development. Kallikrein 8 is induced in neurite injury, and Kallikrein 8 has been shown to be elevated in