Two aspects of biological research are major contributors to the progress in the understanding of cancer etiology and the development of new and improved cancer drugs. The sequencing of the human genome provides us with a basic overview of all our genes and gene products, and the insights into signaling pathways allow us to align crucial components of cellular regulation into an ordered functional context. A comparison of the genes in normal and in tumor cells shows that mutations in the DNA of a limited set of genes are responsible for the multiple stages of tumorigenesis and metastasis....