Introduction: The somatomedins, or insulin-like growth factors (IGFs), comprise a family of peptides that play important roles in mammalian growth and development. IGF1 mediates many of the growth-promoting effects of growth hormone (GH; MIM 139250). Early studies showed that growth hormone did not directly stimulate the incorporation of sulfate into cartilage, but rather acted through a serum factor, termed "sulfation factor," which later became known as "somatomedin" (Daughaday et al., 1972). Three main somatomedins have been characterized: somatomedin C (IGF1), somatomedin A (IGF2; MIM 147470), and somatomedin B (MIM 193190) (Rotwein, 1986; Rosenfeld, 2003).Description: IGF1 N15 Human Recombinant produced in E.coli is a single, non-glycosylated polypeptide chain containing 70 amino acids and having a molecular mass of 7.74kDa. The N15 is stable isotope labeled.The IGF1 N15 is purified by proprietary chromatographic techniques.Physical Appearance: Sterile Filtered White lyophilized (freeze-dried) powder.Formulation: IGF1 N15 protein was lyophilized from a 0.2µm filtered concentrated solution in PBS, pH 7.2.Solubility: It is recommended to reconstitute the lyophilized IGF1 N15 in sterile 18M-cm H2O not less than 100µg/ml, which can then be further diluted to other aqueous solutions.Stability: Lyophilized IGF1 N15 although stable at room temperature for 3 weeks, should be stored desiccated below -18°C. Upon reconstitution IGF1 N15 should be stored at 4°C between 2-7 days and for future use below -18°C. For long term storage it is recommended to add a carrier protein (0.1% HSA or BSA).Please prevent freeze-thaw cycles.Biological Activity: The ED50 as determined by a cell proliferation assay using serum free human MCF-7 cells is less than 2ng/ml, corresponding to a specific activity of > 5.0 × 105 IU/mg.