In the present work we demonstrate that Net1 is critical for mammary gland tumorigenesis and metastasis in the mouse mammary tumor virus (MMTV)-PyMT mouse genetic model of breast cancer, and demonstrate obligate signaling pathways that are regulated by Net1. Moreover, we identify a gene expression signature indicative of Net1 function and use this signature to demonstrate that Net1 contributes to metastasis in human breast cancer patients. The gene discussed is NET1; the disease is breast cancer.