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Short answer: Indeed the proteins in our body are based on amino acids from external food sources. BUT, proteins up-taken from food are ALWAYS disassembled first into amino acids, through specialized enzymes, proteases, (for instance Pepsin in the stomach's gastric juices and Tripsin in the pancreatic juices), during digestion, in the alimentary canal, (gut)....


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NRAS is indeed a molecular switch, as part of the MAP-Kinase signaltransduction pathway it acts in controling the signal which goes downstream and finally will cause the expression of genes. In the case of NRAS this includes genes for proliferation, which is important for tumors. In principle, this looks like shown on this figure (from here): RAS (this is ...


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