The smad proteins and TGFbeta signalling: uncovering a pathway critical in cancer.

The critical role of TGFbeta in development and growth control is well established but the signalling pathway has only recently been elucidated. Identification of the Smads as TGFbeta's intracellular signalling mediators has led to an explosion of information on a novel signalling network that links the cell surface to the nucleus. Many cancers develop resistance to the growth-inhibitory effects of TGFbeta and mutations in signalling pathway components have been discovered that may underly tumour progression.