Figure 5.
Effect of oxygen tension and IGF-1 or IGF-2 on signaling downstream kinases of cell surface receptors during osteogenic differentiation. Similar to Figures 4 and 6, PMSCs were cultured for 14 days in osteogenic differentiation conditions containing 2% FBS in the presence or absence of 100 ng/mL of IGF-1 or IGF-2 in room air (20% O2) or low oxygen levels (1% O2). Treatments were stopped after 3, 7, and 14 days. Immunoblots, in Figure S3, were used to quantify protein levels of (a) p-ERK1/2, (b) p-AKT, and (c) p-RUNX2 over the three days. These kinases/phosphoproteins were normalized to their total kinase/phosphoprotein level and β-actin (two-way ANOVA, P < 0.05, N = 3). X indicates significance between different days without IGFs; # indicates significance of IGF addition compared with no IGFs in the same day; ∗ indicates significance between room air and low oxygen tension.