First Advances Made with the cre/LoxPTechnique in Molecular Endocrinology

The insulin-like growth factor I (IGF-I) is produced in the liver and is believed to mediate the effect of the growth hormone. However, a knockout only in liver IGF-I but slightly disturbs the growth and development of mice. Such mice develop insulin resistance of various organs, including muscle. A knockout in the liver insulin receptor gene also results in insulin resistance. Selective inactivation of the gene for glucokinase (a target of insulin) in pancreatic islets or in the liver suppresses insulin secretion in the pancreas.