Cancer is famous (and difficult to treat) because of the dizzying variation of genetic alterations that can cause it – tumors can acquire tens of thousands of mutations over the course of an individual patient's disease.Unfortunately, the cancer cell lines that are still one of the main research tools to study those genes do not illustrate the same pattern of gene expression as the cancers from which they are derived. That's the conclusion of a study published this week by scientists from the National Cancer Institute.The experiments, which were published in the Oct.