NOS1 and breast cancer: Crosstalk between the NO/NOS system and the Wnt/β-catenin pathway has been reported in two previous studies: treatment with a NO donor improves down-regulated Wnt/β-catenin signaling in renal glomeruli of streptozotocin-induced diabetic rats36 and iNOS gene overexpression and knockdown attenuates and activates, respectively, the Wnt/β-catenin signaling in human colon and breast cancer cell lines37.