Since fish oil can activate nuclear receptors such as PPARγ, we examined if inhibition of ILK
expression by fish oil was mediated by PPARγ. To this end, we tested the cells with GW9662,
a specific PPARγ antagonist. As shown in Fig. 1E, the effects of fish oil on ILK expression
were eliminated in the presence of GW9662, and this was confirmed by PPARγ siRNA (Fig.
1F). Note that fish oil induced PPARγ protein expression (Fig. 1F); this effect was due to
upregulation of PPARγ gene transcription since fish oil stimulated PPARγ gene promoter
activity in separate experiments (not shown). Similar results were also observed with another
PPARγ natural activator, linoleic acid (Fig. 1E).