Why is antagonist inducing the gene? - (Nov/13/2008 )

I have a drug that reduces the level of a certain gene X when compared to control. Now, when I used the antagonist of the drug along with the drug itself, I see a huge increase in the mRNA levels of this gene, even higher than control itself. I know for sure that this antagonist does not have any inverse agonist activity. What other reasons could there be for this effect?
Thanks

The vehicle (solvent for your antagonist) is having some effect? Try dissolving is some other solvent.