IL22 and psoriasis: To further confirm the role of IL-22 in mediating keratinocyte proliferation in psoriasis, we used 10, 20, 40, 80 and 100 ng/mL of IL-22 to stimulate normal human epidermal keratinocytes (HEKs), and the proliferation of cells was detected by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method after 12 h, 24 h and 48 h.