Real-time PCR did not detect amplification of the mutant Kras allele in primary or metastatic cancer cell lines and confirmed the loss of the wild-type Kras allele (Table S3); indicating that the functional differences observed in these cancer cell lines were not caused by differential mutant Kras amplification, but rather by the loss of the wild-type Kras allele. This evidence concerns the gene KRAS and metastatic malignant neoplasm.