 We report that human secretory breast carcinoma (SBC), a rare subtype of infiltrating ductal carcinoma, expresses the ETV6-NTRK3 gene fusion previously cloned in pediatric mesenchymal cancers.     ///    Expression of the ETV6-NTRK3 gene fusion as a primary event in human secretory breast carcinoma..     ///    "ETV6-NTRK3 expression was confirmed in 12 (92%) of 13 SBC cases, but not in other ductal carcinomas. "    ///    Retroviral transfer of ETV6-NTRK3 (EN) into murine mammary epithelial cells resulted in transformed cells that readily formed tumors in nude mice. 