Upregulation of cFLIP promoter activity by forced expression of DDB2. HEK293 cells were co-transfected with cFLIP reporter together with either control vector (pcDNA3) or DDB2-expressing vector (pcDNA3-DDB2). After 24 hrs, the luciferase activity was measured. The plotted values represent means ± S.D. from three independent transfections. The schematic presentation of full-length cFLIP promoter (-920/+43) and its deletion mutants are indicated below. Putative cis-elements are also indicated at positions relative to the transcription initiation site (+1). The construct number at the top indicates the length of the tested promoter region upstream of the putative transcription initiation site (designated by the bent arrow at +1). Luciferase activity is shown relative to the full-length cFLIP promoter (-920/+43). Significant difference to the control for each promoter is indicated.