Insulin-like growth factor-I (IGF-I) is a mitogenic polypeptide that plays
an essential role in the regulation of development and somatic growth of ve
rtebrates, mainly by mediating growth hormone actions. It has clearly been
established that the structure of IGF-I and its biological function has bee
n highly conserved among vertebrates. In this paper, we review the recent d
evelopments in the molecular, biochemical, and physiological properties of
ICF-I in fish.