PPARβ/δ controls pathways that regulate proliferation of LX-2 cells. Stable PPARβ/δ knockdown (KD) was performed by lentiviral transduction of LX-2 cells with a siRNA against PPAR β/ δ. Control LX-2 cells were transduced with the control vector. A) qRT-PCR showed reduced PPAR β/ δ expression in PPARβ/δ KD LX-2 cells. The control values were set to 1. Results are means ± SD of at least three independent experiments performed in triplicate. B-F) Control and PPARβ/δ KD LX-2 cells were starved for 24 h in serum-free media and then treated for 48 h with DMSO (control) or (B) 100 nM GW501516, or (C-F) 100 nM GW501516 in the presence or absence of 10 nM or 100 nM of (C) PD98059, (D) LY294002, (E) JNK inhibitor II, or (F) SB202190. All inhibitors were added 30 min before GW501516 treatment. Cell proliferation was determined by [3H]-thymidine incorporation. Values are expressed as a percentage of the values from DMSO-treated LX-2 cells, which were set to 100%. Values represent means ± SEM from at least five independent experiments performed in triplicate; * = p<0.05 compared to DMSO-treated cells.