p53-independent transcription mediated by the 44-bp element. (A) The 44-bp element enhances or suppresses transcription depending on the promoter. Log phase HL-60 cells were transfected with luciferase reporter plasmid driven by the sv40 promoter (psvluc) or a promoter consisting of 209 bp of the p21 promoter proximal to the transcription startsite (pdluc). Luciferase activity is compared with that of reporter constructs with 3 copies of the 44-bp sequence upstream of the promoter, as indicated. All values are normalized to β-galactosidase expression from cotransfected CMV-βgal reporter to correct for transfection efficiency. The average and standard error of three experiments is shown. (B) Schematic of reporter plasmids used in transfections.