MDM-2 IS NOT INDUCED BY P53 IN HUMAN KERATINOCYTES IN-VIVO

Normal p53 protein protects the genome after DNA damage by delaying re plication and allowing DNA repair. mdm-2 is a recently discovered prot ein that controls p53 activity by binding to and inactivating p53 prot ein. A negative feedback loop has been suggested in which p53 induces mdm-2 expression. We have shown that doses of ultraviolet B radiation that cause mild sunburn clinically, produce thymine dimers in keratino cytes detectable by immunocytochemistry. This causes an elevation of p 53 protein without a concomitant p53-mediated induction of mdm-2. (C) Munksgaard 1996.