A. METABRIC sample data showing that KRAS is altered in 2.6% and mutated in 0.6% of primary tumors from breast cancer patients. B. Kaplan-Meier analysis of patients with SNVs (red) in KRAS vs (wildtype) WT (blue). C-K. Primary tumor weights, numbers of metastases, and metastases normalized to primary tumor weight from orthotopic injection of 4T1 cells transduced with empty vector (EV), Kras WT, or Kras G12D (C-E), MET1 cells transduced with EV, Kras WT, or Kras G12D (F-H), or 6DT1 cells transfected with siControl or siKras (I-K). Each assay was performed twice with 10 mice per group (red and blue points), box whiskers represent min and max points, box boundaries represent the 25th to 75th percentiles, and the horizontal line within the box represents the median. p<0.05 = significant.