Serine protease inhibitor selective for kallikreins. Efficiently inhibits KLK5 and human KLK2, KLK4, KLK5, KLK6, KLK7, KLK12, KLK13 and KLK14. Doesn't inhibit human KLK1 and KLK8. Expressed in the upper epidermis and in skin appendages. Release of soluble SPINK6 is down-regulated by TNF-alpha. IFN-gamma and retinoic acid. Expression is reduced after mechanical and metabolic injury to the skin barrier.