passages.id: split_4_test_685_passage
passages.type: progene_text
passages.text: Both the IL-1 and the TPA - mediated induction result in a drastic increase of AP-1 binding to the downstream site of the enhancer ( uPA 3' TPA - responsive element ) , while a mostly qualitative change , resulting from the interplay between ATF-2 homodimers and c-Jun - ATF-2 heterodimers , takes place at the upstream AP-1 element .