Signal cell transformation

Ral has attracted much interest in recent years, not least because it was demonstrated to mediate part of Ras function as described above. In contrast to Rap, which rather inhibits Ras signaling, Ral is part of one of the essential Ras-activated pathways. Moreover, it has proved to be acting in parallel with the Raf pathway in cell transformation induced by oncogenic Ras [37, 77]. The case of Ral demonstrates the complexity - and the incomplete knowledge and understanding - of signal transduction. Ral can also be activated by Rap mediated by Rif [103] and, alternatively, by binding of a calcium/calmodulin complex to the Ral C-terminus which obviously does not affect the nucleotide state of Ral [111]. 

The Ras signal transduction cascade is of extreme physiological importance. It is central to the regulation of cell growth and differentiation, and false regulation of this signal pathway can be one of the critical steps leading to cell transformation.151 A... 

Huang YL, Shen CK, Luh TY, Yang HC, Hwang KC, Chou CK (1998) Blockage of apoptotic signaling of transforming growth factor-beta in human hepatoma cells by carboxyfullerene. Eur. J. Biochem. 254 38—43. 

Fig. 3.2. The individual steps of intercellular communication. Upon reception of a triggering stimulus, the signal is transformed into a chemical messenger within the signaling cell. The messenger is secreted and transported to the target cell, where the signal is registered, transmitted further, and finally converted into a biochemical reaction. Not shown are processes of termination or regulation of communication which can act at any of the above steps.

Rogelj, S., Weinberg, R. A., Fanning, P. and Klagsbrun, M. (1988). Basic fibroblast growth factor fused to a signal peptide transform cells. Nature 331, 173-175. 

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