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Ras Group

The ras genes encode proteins important for the regulation of cell growth. The information that human tumors often carry activating mutations in the ras-genes argue for their importance in the development of cancer. The mutations change the encoded proteins such that they are no longer down-regulated.

Ras proteins are guanine-nucleotide binding proteins. When cells are stimulated with growth factors, the Ras-proteins are induced to bind GTP as opposed to GDP. When bound to GTP, the Ras-protein can interact with a series of effectors, who become activated and mediate the signaling that lead to cell proliferation. Ras-GTP is short-lived because a cellular protein catalyzes the hydrolysis of the GTP by Ras itself. Thus, continuous stimulation is necessary to maintain Ras in the active form.

An exception is when the cell expresses the cancer-associated mutants. These forms cannot mediate hydrolysis of the bound GTP as effectively and therefore stay active in the absence of growth stimulatory signals.

We study the effect of oncogenic Ras in cell culture, where Ras induces a form of cell growth that lead to high densities of cells - focus formation. We try to understand which of the gene expression changes that oncogenic Ras induce, are important for this type of growth.