Furthermore, inflamed DD skin displayed an increase of proteases, especially matrix metallopeptidase 1 (MMP1), serine protease 3 (PRSS3) and kallikrein serine proteases KLK6, 9, 12, 13 that are able to cause barrier damages when overexpressed and which actions are mainly neutralized by SPINK6 [55] and serpins. The gene discussed is KLK4; the disease is dentin dysplasia.