Fig. 2. EGCG does not activate the insulin signaling pathway.

(A) Mouse primary hepatocytes were treated with EGCG (1 μM) or insulin (10 nM) for 5 min to 3 h. Cellular levels of IRS1 phosphorylation at tyrosine⁶¹⁵ and phospho-/total Akt were measured by immunoblotting. (B) and (C) Hepatocytes were pre-treated with LY294002 for 30 min as noted before the treatment with EGCG or insulin for 3 h in the serum-free Williams’ E medium. Cells were then washed with a pre-warmed glucose-free DMEM medium for 3 times, and subsequently stimulated by cAMP/dexamethasome (Dex) in the presence of EGCG or insulin for 3 h in the glucose-free DMEM medium. Gluconeogenic substrates were added to cells as noted. The glucose production via gluconeogenesis was quantified and calculated as detailed in “Materials and Methods”. Transcripts of PEPCK and G6Pase genes were quantified by the Taqman Real-time PCR and normalized to GADPH. **: P < 0.01 vs. cells treated with Dex/cAMP.