MULTIPLE PATHWAYS CONTROL CELL-GROWTH AND TRANSFORMATION - OVERLAPPING AND INDEPENDENT ACTIVITIES OF P53 AND P21(CIP1 WAF1/SDI1)/

Many tumour therapies act by inducing a cellular damage response pathw ay mediated by the tumour suppressor protein p53. Alternative outcomes of p53 induction include apoptosis of transient cell-cycle arrest, bo th thought to require the transcriptional activity of wild-type p53. C urrent research highlights the action of a p53-activated gene, p21(Cip 1/WAF1/Sdi1), which encodes a cyclin-kinase inhibitor important in med iating p53-dependent cell-cycle arrest, while programmed cell death in response to DNA damage requires transcriptionally active p53 but not activation of p21(Cip1/WAF1/Sdi1). This review examines the roles of p 53 and p21(Cip1/WAF1/Sdi1) in controlling cell proliferation, in the l ight of a new study on expression of p53 and p21 (Cip1/WAF1/Sdi1) in s quamous cell carcinoma of the larynx. (C) 1997 John Wiley & Sons, Ltd.