The TetRE-EGFRtr-SV40 transgene was designed with the tetracycline operator (tetO; also called tetracycline-responsive element (TRE, TetRE) or tet-operator) and cytomegalovirus minimal promoter, a 2.3 kb C-terminal truncated mouse epidermal growth factor receptor cDNA sequence (EGFR-tr; encoding amino acid 1-690 followed by a TGA stop codon), and an SV40 intron/polyA sequence. This 4.5 kb transgene was microinjected into one-cell (C57BL/6 x SJL) mouse zygotes. Mice from founder lines 2-9 were bred with C57BL/6;SJL wildtype mice to establish the colony. (J:68692)