The chicken beta-actin (CAG) promoter, a loxP flanked STOP cassette, and human FGFR2 isoform IIIb cDNA with the kinase K660N domain activating mutation were inserted into the mouse collagen A1 locus. Upon cre-mediated recombination, the STOP cassette is excised promoting expression of the mutant FGFR2. (J:214230)