Figure 1. Generation and testing of the MIP1-CreERT transgenic mouse. (A) Transgenic construct containing MIP promoter, CreER gene and hGH and agarose gel with genotyping products from negative (1,2,5,7) and positive (3,4,6) founder lines, as well as control DNA (8); Expression of β-galactosidase in the pancreas of ROSA-LacZ:MIP1-CreERT[Tmx]: (B) Frozen sections of the pancreas from ROSA-LacZ:MIP1-CreERT mice injected or not with tamoxifen, were stained for β-galactosidase activity (blue staining); (C) frozen sections of pancreas from ROSA-LacZ:MIP1-CreERT [Tmx] mice (injected with tamoxifen) were stained for β-galactosidase (GREEN), insulin (BLUE) and glucagon (RED) antibodies. Note almost complete overlap of β-galactosidase staining and insulin staining, and the absence of such overlap of β-galactosidase with glucagon staining. Corresponding image of a control islet ROSA-LacZ:MIP1-CreERT[oil] staining for β-galactosidase, insulin and glucagon shows lack of β-galactosidase staining in the islet; (D) MIP1-CreERT transgene expression is specific for pancreatic islets: RT-PCR amplification of Cre in cDNA obtained from various tissues of MIP1-CreERT mice. Densitometry of PCR fragment in an EtBr stained gel (n = 3). Control – actin (not shown).