The intragenic AP-1 binding sites are fully responsible for the PMA-dependent enhancer activity of fragment 5103.

<p>HeLa cells were transiently transfected with 200 ng of the following constructs: the control vector pTK, the pTK-5103s-wt, pTK-5103as-wt, pTK-5103as-totmut, pTK-5103as-mut1, pTK-5103as-mut2, pTK-5103as-mut3 or pTK-5103as-mut1+2 reporter construct. All transfection mixtures additionally contained the pRL-TK (1 ng), in which a cDNA encoding the <i>Renilla</i> luciferase gene is under the control of the HSV TK promoter. At 24 h post-transfection, cells were mock-treated (-) or treated with PMA (+) (20 nM). Luciferase activities (<i>Firefly</i> and <i>Renilla</i>) were measured in cell lysates 48 h after transfection. Results are expressed as Luciferase<i>_Firefly</i>/[Proteins]*Luciferase<i>_Renilla</i> and presented as histograms indicating the luciferase activities of each construct relative to that of the control vector pTK, which was assigned an arbitrary value of 1 in absence of PMA. Means and standard errors of the means from three independent transfection experiments each performed in triplicate are indicated. The PMA induction of each TK construct is written in the upper part of the Figure (in fold). * indicates p<0.05 compared with the wild-type construct.