Abstract: Objective To observe the relationship between p21and development of psoriasis.Methods The expression of p21^WAF1/CIP1 in twelve psoriatic and five normal epidermis was studied by dot hyhridization, in situ hvbridization and immunohistochemistry.Results In psoriatic epidermis, the expression of p21^WAF1/CIP1, was in whole layers of epidermis, and was significantly inereased eompared with that of normal skin. In normal epidermis, its expression was in upper laver of epidermis.Conclusion These results indicate thai p21^WAF1/CIP1 might be assoeiated with differentiation of normal keralinoevtes and might play a role in abnormal differentiation of psoriatic keratonoeyles.

Key words: Psoriasis, p21^WAF1/CIP1