A mutant human epidermal factor receptor cDNA with a C-to-T nucleotide substitution in exon 20 that replaces threonine with methionine at amino acid position 790 (T790M) was cloned between a tetracycline-responsive element and an intron and polyadenylation signal from the mouse protamine 1 gene. Mice with this transgene that express the tetracycline transactivator (tTA) or reverse transactivator (rtTA) under control of a tissue-specific promoter can be induced to express the mutant gene in tissues or cell types of interest by administration/withdrawal of doxycycline. Five lines were established (8, 22, 37, 45, and 71) and line 8 is entered as a representative line.