Figure 4

In Mvt1 cells, insulin elevates c-Myc, MMP-9 and phosphorylated Akt, and results in increased proliferation. (A) Akt phosphorylation in Mvt1 cells after insulin stimulation. Mvt1 cells were serum-starved for four hours prior to stimulation with increasing concentrations of insulin. Cells were then harvested and subjected to SDS PAGE and Western blotting with antibodies to insulin receptor-β (IR-β), phosphor-Akt^Ser473 and Akt, phospho-p42/p44^{Thr202Tyr/204} and p42/p44. Β-actin was included as a loading control. (B) Mvt1 cells were seeded at a density of 1 × 10⁴ cells/ml in 24-well plates and stimulated with either 10 nM or 100 nM insulin in growth medium containing 0.5% FBS. After 72 hours, cells were trypsinized and counted using a haemocytometer and trypan blue exclusion. Cell counts are representative of three independent experiments. Error bars represent SEM, *, P ≤ 0.05. (C) Mvt1 cells were stimulated with 10 nM or 100 nM insulin for between 10 and 60 minutes. Previously, cells were grown in medium containing 0.5% FBS for 72 hours. After stimulation, cells were harvested and subjected to SDS PAGE and Western blotting with antibodies to c-Myc and MMP-9. β-actin was included as a loading control.