The function of SPINK9 (serine peptidase inhibitor Kazal type 9, ENSG00000204909) is as follows. Serine protease inhibitor which specifically inhibits KLK5. May contribute to the regulation of the desquamation process in skin by inhibiting KLK5. {ECO:0000269|PubMed:19190773, ECO:0000269|PubMed:19194479}.