IGFs, or insulin-like growth factors, are polypeptide growth factors known for their ability to stimulate the proliferation and survival of various cell types, including those found in muscle, bone, and cartilage tissue when studied in vitro. They are primarily synthesized in the liver, though various tissues produce them at specific times. Belonging to the Insulin gene family, which also includes insulin and relaxin, IGFs share structural and functional similarities with insulin but exhibit significantly greater growth-promoting activity.

IGF-II expression is influenced by placenta lactogen, while growth hormone regulates IGF-I expression. Both IGF-I and IGF-II signal through the tyrosine kinase type I receptor (IGF-IR), though IGF-II can also utilize the IGF-II/Mannose-6-phosphate receptor pathway. Mature IGFs are formed through proteolytic processing of inactive precursor proteins, which contain N-terminal and C-terminal propeptide regions.

Recombinant Human IGF-I and IGF-II are globular proteins composed of 70 and 67 amino acids, respectively, and each contains three intra-molecular disulfide bonds. The calculated molecular weight of Recombinant Human IGF-II is 7.5 kDa.