A MEK dominant negative mutant or treatment with the kinase inhibitor UO126 does not affect transcription from the uPA minimal promoters in PC3 cells. PC3 cells were cotransfected with the reporter plasmids used in Figure 1 and with increasing amounts of a plasmid constitutively expressing a MEK dominant negative mutant (MEK^DN). The uPA minimal promoter construct (A) was only marginally affected by MEK^DN. Error bars indicate SD. (B) Quantitation of the data in panel A is as in Figure 1 but expressed as fold decrease. (C) Quantitation of the results obtained with the UO126 treatment of uPA-MP–transfected PC3 cells. The cells were given an amount of DMSO, as a control, equivalent to that containing 50 or 100 μM UO126. Also in this case, the results are expressed as fold decrease.