Fig. 6. Effects of NaSal on activation of NF-B transcription by TC10, Cdc42, or MEKK1. COS cells were cotransfected with plasmids expressing wild-type or activated Cdc42, wild-type or activated TC10, or a constitutively active MEKK1 and a reporter plasmid containing NF-B binding elements fused to a firefly luciferase gene. Six h posttransfection, cells were maintained in serum-free medium for 20 h and then transferred to fresh serum-free medium in the absence (-) or presence (+) of 20 mM NaSal for 6 h. Samples to be tested for recovery of NF-B activation were transferred to fresh medium in the absence (-) of NaSal for an additional 20 h. Cells were then harvested, lysed, and examined for luciferase expression. -, mock NaSal treatment; +, 6-h NaSal treatment; -/-, mock NaSal treatment followed by a change to fresh serum-free medium and incubation for an additional 20 h; +/-, NaSal treatment for 6 h followed by a change to fresh serum-free medium and incubation for an additional 20 h. The columns represent the average percentage of activation relative to TC10 75L (for TC10 and TC10 75L samples), Cdc42 61L (for Cdc42 and Cdc42 61L samples), or MEKK1 (for MEKK1 samples) in the absence of NaSal for three experiments, and the error bars show the range. The level of GTPase or MEKK1 expression was determined by immunoblotting to be similar for all samples.