The mouse promoter was used to drive tamoxifen-inducible, melanocyte-specific expression of a floxed cre/ESR1 fusion containing the aminoacid substitution G521R followed out of frame by a constitutively active Hras1 with the G12V amino acid substitution, an IRES, and the mouse cDNA for Trap1a with its polyadenylation signal. Removal of the floxed cre/ERT fusion is required to express downstream genes. Eight founders were generated (TiRP-1-5, TiRP-5-6, TiRP-8/9A, TiRP-8/9B, TiRP-10A, TiRP-10B, TiRP-14 , and TiRP-16) and each contained concatemers of the transgene in head to tail or tail to tail orientations. Cre mediated recombination removes all but one copy of the recombined transgene. In the case of line 14, cre mediated recombination also results in the removal of the polyadenylation site following Trap1a.