inhibits Spry1 down-regulation of the Col-TRE driven reporter gene. (A) Schematic representation of the reporter construct 3xcolTRE-tk-Luc; the Luciferase expression is driven by the thymidine kinase promoter of the herpes simplex virus (tk, nt -105 to +51) and three copies of the TRE sequence of the human collagenase gene (colTRE, nt -73 to -65). (B, C) HeLa cells were co-transfected with the colTRE-Luc reporter construct (0.5 μg), expression vectors (0.5 μg) coding for E1A13S and/or Spry1 and c-Jun as indicated. Empty expression vectors were added to keep the amount of transfected DNA constant. 63 h after transfection cells were lysed and Luciferase activity was determined. Total lysates were immunoblotted to monitor the presence of expressed proteins with respective antibodies against E1A13S, Spry1 and c-Jun. Results are mean ± S.E.M. between duplicates.