KLK8 (kallikrein related peptidase 8) is a secreted serine protease with diverse physiological functions across multiple tissues. In the nervous system, KLK8 plays a critical role in synaptic plasticity and memory formation, with knockout mice showing suppressed long-term potentiation in the hippocampus 1. The protein cleaves pro-HGF to activate the HGF/Met signaling pathway, which can mediate neuroinflammation in diabetic conditions, contributing to depression-like behaviors 2. In skin biology, KLK8 functions in keratinocyte proliferation and desquamation through degradation of adhesive molecules connecting epidermal layers 1, with its expression strongly correlating with keratinocyte proliferation marker MKI67 in wound healing 3. KLK8 also drives pathological processes, including diabetic cardiac fibrosis through endothelial-to-mesenchymal transition mediated by VE-cadherin cleavage and TGF-β1 signaling 4. In psoriasis, KLK8 creates a positive feedback loop with IL-17A signaling, promoting histone H4K12 lactylation and keratinocyte hyperproliferation 5. Clinically, KLK8 serves as a favorable prognostic marker in ovarian cancer, with higher expression associated with longer disease-free survival 6. The protein's multifunctional nature reflects its tissue-specific roles in both physiological processes and disease pathogenesis.