<；P>；PROBLEM TO BE SOLVED: To provide a novel drug effective for promoting pancreatic &beta； cell growth, increasing blood insulin level, decreasing blood glucose level, and treating or preventing diabetes. <；P>；SOLUTION: A drug enhancing the function of ERK proteins in the liver is used as a pancreatic &beta； cell growth promoter, a blood insulin level increasing agent, a blood glucose level decreasing agent and a therapeutic or prophylactic agent for diabetes. A substance enhancing the function of ERK proteins in the liver is not limited to a particular substance and can be chosen from various substances such as substances enhancing the activity of MEK proteins, substances activating endogenous MEK proteins and expression vectors expressing genes encoding active MEK proteins. Such substances may be prepared using known techniques or may be those commercially available. <；P>；COPYRIGHT: (C)2009,JPO&INPIT
