Overexpression of cMyc, a global regulator of transcription50 and a known Wnt target gene,51 has previously been reported to induce mammary carcinomas in mice52 and found to be overexpressed in the majority of human breast tumors.53 Given Wnt pathway activation was only apparent in a subset of epithelial cells at an early time point, it is unclear whether these tumors arise because of Wnt activation in specific cell types, which one could speculate to be mammary stem cells or because of accumulation of other oncogenic mutations. The gene discussed is MYC; the disease is breast carcinoma.