In molecular biology, Ras is the name of a protein, the gene that encodes it, and the family and superfamily of proteins to which it belongs. Proteins in the Ras family are very important molecular switches for a wide variety of signal pathways that control such processes as cytoskeletal integrity, proliferation, cell adhesion, apoptosis, and cell migration. Ras and ras related proteins are often deregulated in cancers, leading to increased invasion and metastasis, and decreased apoptosis. The Ras superfamily includes the Ras, Rho, and Rab families.

RAS is a G protein (specifically a small GTPase): a regulatory GTP hydrolase that cycles between two conformations – an activated or inactivated form, respectively RAS-GTP and RAS-GDP. It is activated by guanine exchange factors (GEFs, eg. CDC25, SOS1 and SOS2, SDC25 in yeast), which are themselves activated by mitogenic signals and through feedback from Ras itself. It is inactivated by GTPase-activating proteins (GAPs, the most frequently cited one being RasGAP), which increase the rate of GTP hydrolysis, returning RAS to its GDP-bound form, simultaneously releasing an inorganic phosphate. RAS is attached to the cell membrane by prenylation, and in health is a key component in many pathways which couple growth factor receptors to downstream mitogenic effectors involved in cell proliferation or differentiation (Reuter et al., 2000). RAS activates a number of pathways but an especially important one seems to be the mitogen-activated protein (MAP) kinases, which themselves transmit signals downstream to other protein kinases and gene regulatory proteins (Lodish et al., 2000).

RAS in cancer

---

Mutations in the RAS family of proto-oncogenes (comprising H-RAS, N-RAS and K-RAS) are very common, being found in 20% to 30% of all human tumours (Bos JL, 1989).

More on [ Ras ]

NPR Topics: Authors

Carter's New Thriller Mixes Murder, Love And Politics
Fri, 18 Jul 2008 12:40:00 -0400
Novelist Stephen Carter, who is also a professor at the Yale Law School, says his latest novel, Palace Council, is a thriller, a conspiracy, a love story and historical fiction. And the process of writing it was "utterly exhausting."
Celebrating A Dutch Mystery Writer's Varied Life
Fri, 18 Jul 2008 10:48:00 -0400
Mystery novelist Janwillem Van de Wetering was once a motorcycle gang member in South Africa, an aspiring monk in Kyoto, Japan and a policeman in Amsterdam. The Dutch author of The Hollow-Eyed Angel, The Blond Baboon and The Maine Massacre died July 4 at the age of 77.
Author Transforms Himself From Schlub To Stud
Fri, 18 Jul 2008 10:00:00 -0400
They may be considered clumsy and unattractive, but one author discovers that schlubs aren't necessarily losers.
Joe Wambaugh: The Writer Who Redefined LAPD
Fri, 18 Jul 2008 14:24:00 -0400
Wambaugh, who spent years on the force, wrote the best-selling book The Onion Field in three months during a leave of absence from the department. Over the decades, his realistic and multidimensional portrayals of L.A. cops have helped tranform their public image.
Author Scrutinizes U.S.-Pakistan Relations
Fri, 18 Jul 2008 08:45:00 -0400
Pakistan has been an ally of the United States in the so-called war on terror, but some wonder whether the U.S. foreign policy toward Pakistan is really successful. Shuja Nawaz, author of Crossed Swords: Pakistan. Its Army and the Wars Within, discusses the relationship between the U.S. and Pakistan, and the role of the Pakistan army in the region.
Searching For Bodies In Chelsea Cain's Portland
Thu, 17 Jul 2008 00:00:00 -0400
Crime writer Chelsea Cain sees danger lurking in the most pastoral corners of the polite Northwest city she calls home. Ketzel Levine dares to search for skeletons with the writer.

Subscribe to Authors RSS feed