The Insulin-like Growth Factor 1 Receptor (IGF-1R antibody) is a trans-membrane receptor that is activated by Insulin-like Growth Factor (IGF-1 antibody). IGF-1 stimulates mitosis and inhibits apoptosis thus enhancing cell survival. It is expressed in all 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. Studies show IGF-1 to be a likely predictor for resistance to anti-EGFR antibody treatment in K-RAS wild type colorectal cancer. IGF-1 and K-RAS analysis may offer an effective strategy for selection of responding colorectal cancer patients.