Supplemental Data

Supplemental Data

Files in this Data Supplement:

• Supplemental Table 1 - Comparison of IGF-I signaling responses in human osteoblasts from young and old control (OB/C) donors.
• Supplemental Figure 1 - IGF-I stimulation of Akt, GSK-3, and Erk phosphorylation in osteoblastic cultures from young and old control subjects (OB/C). OB/C from young (filled circles) and old (empty squares) subjects were studied in the absence or presence of 100 nmol/l IGF-I for the indicated times. Phosphorylation of Akt on Thr³⁰⁸ and Ser⁴⁷³, of GSK-3α and β, and of Erk-1 and -2, respectively, was evaluated by immunoblotting with specific antibodies, as described under Research Design and Methods. Levels of phosphorylated proteins were normalized to the respective basal. Data are expressed as mean ± SE of n = 2 young OB/C and n = 3 old OB/C, analyzed in triplicate. *P < 0.05 vs. respective basal.
• Supplemental Figure 2 - Tyrosine phosphorylation of IGF-I receptor and IRS proteins in osteoblasts from control (OB/C) subjects. OB/C were studied in the basal state and after IGF-I 100 nM stimulation for the indicated times (A) or for 2 min (B). Cell lysates were analyzed directly with phosphotyrosine (PY) immunoblot (A), or subjected to immunoprecipitation (IP) with antibodies to IRS-1 followed by immunoblotting (IB) with antibodies to PY. In each panel, representative immunoblots are shown. (A) Tyrosine phosphorylation of IRS proteins (top) and IGF-I receptor (IGF-I R) (bottom). (B) Tyrosine phosphorylation of IRS-1.