S100A9 and psoriasis: Strikingly, global or skin-specific transgenic mice overexpressing mouse sPLA2-IIF (Pla2g2f-TG) spontaneously develop psoriasis-like epidermal hyperplasia and alopecia, with increased expression of various psoriasis markers such as S100A9 and IL-36α [26], suggesting that increased expression of this sPLA2 alone could trigger psoriasis.