(A) Hepatic MTP protein levels. (B) Hepatic MTTP mRNA levels. (C) Hepatic MTTP mRNA levels. HepG2 cells were transduced with control LacZ or FoxO1 vector or FoxO1 plus CA-Akt vector (MOI, 25 pfu/cell), followed by the determination of MTTP mRNA levels after 24-h incubation in the presence or absence of insulin (100 nM). (D) FoxO1 subcellular distribution. FoxO1 vector-transduced HepG2 cells were incubated with control or CA-Akt vector for 24 h, followed by immunoblot analysis of FoxO1 protein levels in cytosolic and nuclear fractions (E). (F) Hepatic MTTP mRNA levels. HepG2 cells were treated with PI3K activator IRS-1 (Y608) peptide (IRS-1, 1 μM) or inhibitor LY294002 (LY, 10 μM) in the presence and absence of insulin for 24 h. (G) FoxO1 induction of MTP promoter activity. HepG2 cells were cotransfected with 2 μg each pGH11 and pCMV-LacZ vectors in the presence of Adv–FoxO1-ADA vector at doses ranging from 50 to 400 pfu/cell, followed by luciferase activity assay after 24-h incubation. Likewise, HepG2 cells were cotransfected with pGH11 and pCMV-LacZ plasmids together with FoxO1 (H) or FoxO1-ADA (I) vector at a fixed dose (MOI, 100 pfu/cell) in the presence and absence of insulin for the determination of luciferase activity. (J) FoxO1 subcellular distribution. FoxO1 vector-treated HepG2 cells were incubated in the absence or presence of insulin for 30 min, followed by immunoblot analysis of FoxO1 in cytosolic and nuclear fractions (K). (L) Insulin inhibition of MTP promoter activity. FoxO1 vector-transduced HepG2 cells were transfected with MTP promoter–directed reporter system in the presence or absence of insulin. Cells were assayed for luciferase activity at different times. Data represent 3–5 experiments. *P < 0.05, ^#P < 0.001 versus controls.