The collagenase gene promoter contains a TPA and oncogene-responsive unit encompassing the PEA3 and AP-1 binding sites.

PEA3 is a transcription factor which binds to the polyoma virus enhancer and whose activity is regulated by the expression of a number of oncogenes. We show here that PEA3 also binds specifically to the collagenase and fos cellular promoters. On the collagenase promoter, PEA3 acts synergistically with AP-1 to achieve maximum levels of transcription activation by 12-O-tetradecanoylphorbol-13-acetate (TPA), and non-nuclear oncoproteins, thereby defining a TPA- and oncogene-responsive unit (TORU). From a comparative study of the collagenase TORU and the analogous polyoma virus TORU, we conclude that both the binding affinity of the PEA3 motif and the spacing between PEA3 and AP-1 modulate transcription activation induced by oncogene expression.