KLK4 (kallikrein related peptidase 4) is a chymotrypsin-like serine protease that plays a critical role in dental enamel formation during tooth development 1. The enzyme is expressed during the transition from secretory to maturation stage of amelogenesis and functions throughout the maturation phase 1. KLK4's primary function is to aggressively degrade the retained organic matrix following termination of enamel protein secretion, facilitating the orderly replacement of organic matrix with mineral to generate harder, less porous enamel 2. Studies of Klk4-ablated mice demonstrate that without functional KLK4, enamel remains soft and protein-rich, with crystallites failing to properly interlock despite growing substantially in width and thickness 1. Mutations in KLK4 cause autosomal recessive amelogenesis imperfecta, characterized by soft, porous enamel containing residual protein 23. Beyond dental development, KLK4 has clinical significance in cancer, particularly ovarian carcinoma, where higher expression correlates with poor prognosis, increased tumor grade, and clinical stage 4. Genetic variations in KLK4 also contribute to dental caries susceptibility 56, highlighting its broader role in oral health.