The regulation and function of p21^ras in T cells

In T cells, activation of the guanine-nucleotide-binding proteins encoded by the p21^ras proto-oncogene is a common response to triggering of the T-cell antigen receptor, the adhesion molecule CD2 and the receptor for the cytokine interleukin 2. This article by Julian Downward and colleagues describes the mechanisms of p21^ras regulation and the potential function of p21^ras in T cells, and discusses the evidence that multiple intracellular pathways may be involved in the coupling of cell surface receptors to p21^ras.