Psoriasin (S100 A7) was discovered two decades ago as a protein abundantly 
expressed in psoriatic keratinocytes. Even though much scientific research has 
been carried out on the characterization of psoriasin, only recent studies point 
to an important role of psoriasin as an antimicrobial and immunomodulatory 
protein in skin and other epithelia. In this review, we provide an overview of 
the major findings in psoriasin research and discuss novel studies highlighting 
the role of psoriasin as an important effector molecule of the cutaneous 
barrier.