Interestingly, the tumor cells were largely devoid of epithelial markers, Epcam (Figure S2A) and cytokeratins (Figure S2B, D), but strongly expressed vimentin (Figure S2B, C), indicating that in non-transgenic mice transition into the mesenchymal state is favored, possibly as a consequence of an interaction with the host immune system. This evidence concerns the gene VIM and neoplasm.