The transgene consists of a 220 bp fragment of the human GHRH gene encoding the N-terminal 31 amino acid signal peptide and a 40 amino acid form of the protein fused to a mouse Mt1 promoter. Overexpression of the human GHRH transgene was observed by in situ hybridization analysis of pituitary tumors from transgenic animals over 10 months of age. (J:80892)