Abstract: Establishment of pancreatic islet-like insulin producing cells by inducing differentiation of ES/iPS cells has been reported. However, no technique has been developed so far for producing functional pancreatic islet insulin-positive cells in a large amount. In addition, there are concerns regarding rejection responses, accidental immune responses, etc. The present invention provides pancreatic islet-like cells having Mycl gene introduced thereinto and a method that comprises inducing proliferation of pancreatic islet-like cells by transient expression of Mycl gene and then inducing degradation thereof into insulin producing cells.