Figure 6. Extracellular nucleotides and P2Y₁₃ expression regulate ERK1/2 signaling.

(A) HepG2 cells were pre-treated with 12 µM DLPC for 30 min. and then incubated with and without ADP (100 µM) for 0, 5, 15 and 30 min in DMEM serum-free media. Cell lysates were immunoblotted for phosphorylated ERK1/2. Histograms represent densitometry analysis of p-ERK1/2 normalized to β-actin and expressed as mean percent change ± SD of 3 independent experiments. *P<0.01 vs Ctrl, **P<0.05 vs ADP 5 min. (B) HepG2 cells were transfected with either negative control (si-Ctrl) or P2Y₁₃ siRNA (si-P2Y₁₃) and incubated for 24 h. Cell lysates were immunoblotted for phosphorylated and total ERK1/2. Histograms represent band densitometry analysis of the ratio of phospho-ERK1/2 (p-ERK1/2) to total ERK1/2 (t-ERK1/2) and are expressed as mean ± SD for 3 independent experiments. *P<0.05 vs. control siRNA.