KRAS and cancer: Comparing the cell lines derived from the two paired primary tumors and metastases derived from the same mice, the frequency of LOH at Kras was greater among the cancer cell lines derived from each metastasis (8.3% and 33.3%) than those derived from the corresponding primary pancreatic tumor (0% and 17.6%, respectively) (p=0.16 and p<0.05, respectively) (Fig. 5A), suggesting Kras LOH might promote metastasis in vivo.