The Insulin-like Growth Factor 1 Receptor (IGF-1R) is a
transmembrane receptor that is activated by Insulin-like Growth Factor (IGF-1)
and by the related growth factor IGF-2. It belongs to the large class of
tyrosine kinase receptors. IGF-1 stimulates mitosis and inhibits apoptosis thus
enhancing cell survival. The IGF-1 receptor is expressed in all cell types and
tissues and is highly over-expressed in most malignant tissues. IGF-1 has been
shown to induce hypoxia-inducible factor-1 (HIF-1) mediated vascular endothelial
growth factor (VEGF) expression. Other studies have shown IGF-1 to be a possible
predictive factor for resistance to treatment with anti-EGFR monoclonal
antibodies in K-RAS wild type colorectal cancer. Combined IGF-1 and K-RAS
analysis may represent an effective strategy for a better selection of
responding colorectal cancer
patients.