Figure 4. PKC-θ knockdown offsets the effects of the antagonism of EP2/EP4 signaling by compensatory induction of PKC-α.

A, Knockdown using PKC-θ siRNA was performed in BxPC-3 cells and confirmed by immunoblotting. Cells transfected with negative control siRNA and PKC-θ siRNA were stimulated with IGF-1 for 48 h or 20 min in the absence or presence of AH6809/GW627368X pretreatment for 3 h, and then tested by growth stimulation assays and immunoblotting. The A₅₅₀ values for untreated cells were assigned as 100% and the relative percentages for treated cells are shown. The relative levels of phospho-MEK and -ERK were calculated using ImageJ software. Columns, mean percentages (n = 6); bars, SD. B, The expression levels of PKC-α, PKC-β, PKC-γ, PKC-δ, PKC-ε, PKC-η, PKC-θ, PKC-ζ, PKC-ι, and β-actin mRNA were determined in BxPC-3 cells transfected with negative control siRNA and PKC-θ siRNA.