“…Members of the AP-1 family can also crossdimerize with ATF/CREB transcription factors [Hai and Curran, 19911. The c-jun gene is expressed in response to a variety of external stimuli, including growth factors, W radiation, ionizing radiation, oxidative stress, and various chemical agents [Sherman et al, 1990;Devary et al, 1991;Bergelson et al, 19941. Elevation of c-jun mRNA levels in response to these stimuli is a consequence of increased transcription of the gene [Quantin and Breathnach, 1988;Ryder and Nathans, 1988;Wu et al, 1989;Sherman et al, 1990;Devary et al, 1991;Chauhan et al, 1993;Bergelson et al, 19941. We have recently analyzed the promoter of the c-jun gene in HeLa cells during U V irradiation, which induces the gene > 100fold [Devary et al, 1991;Rozek and Pfeifer, 19931. Six transcriptional activator proteins were detected along the c j u n promoter region in HeLa cells. Surprisingly, no changes in protein-DNA interactions were observed during the UV response, indicating that induction of the gene was mediated by preformed protein-DNA complexes at the promoter.…”