We have previously reported that Hras is mutated and activated in approximately 50% of tumors arising in MMTV-Wnt1 mice (31), and we have previously confirmed that forced expression of HrasQ61L, KrasG12D, or even Nras WT in MMTV-Wnt1 mice led to rapid tumor appearance (19, 53). This evidence concerns the gene NRAS and neoplasm.