The uPA minimal promoter element responds to a constitutively active MEK kinase and to a MEK/ERK chimeric kinase. HeLa cells were transfected with a reporter construct in which the luciferase gene was driven by the minimal promoter element of the uPA gene. The cells were also cotransfected with increasing amounts of a plasmid constitutively expressing the active form of MEK (MEK^A; panel A) or the MEK/ERK chimeric kinase (MEK/ERK^A; panel B). The uPA minimal promoter element displays a dose-dependent response to both the constitutively active kinases. RLU indicates relative light units. Error bars indicate SD. (C-D) Quantitation of the data in panels A and B, respectively. Variation in transcriptional activation is expressed as fold induction relative to the minimal promoter construct alone.