This is the N-terminal three beta strands of involucrin, a protein present in keratinocytes of epidermis and other stratified squamous epithelia. Involucrin first appears in the cell cytosol, but ultimately becomes cross-linked to membrane proteins by transglutaminase thus helping in the formation of an insoluble envelope beneath the plasma membrane. Apigenin is a plant-derived flavanoid that has significant promise as a skin cancer chemopreventive agent. It has been found that apigenin regulates normal human keratinocyte differentiation by suppressing it and this is associated with reduced cell proliferation without apoptosis. The downstream part of the protein is represented by the family Involucrin, pfam00904.