1. Genetics of RAS Signaling in Drosophila.- I. Introduction.- II. Background to the Experimental Systems.- III. Protein Tyrosine Kinase Receptors.- IV. Linking RAS with Tyrosine Kinase Receptors.- V. A Kinase Cascade Downstream of RAS.- VI. Nuclear Events.- VII. Concluding Remarks.- 2. RAS-Mediated Signal Transduction in C. elegans.- I. Introduction.- II. Genetic Approaches Used to Study Vulval Signal Transduction.- III. Genetic and Molecular Analysis of the let-60 RAS Gene.- IV. Genes Acting Upstream of RAS.- V. Genes Acting Downstream of RAS.- VI. Multiple Functions of the let-60 RAS-mediated Signal Transduction Pathway During C elegans Development.- 3. Mammals I: Regulation of RAS Activation.- I. Introduction.- II. Growth Factor/Cytokine Signaling.- III. Growth Factor Cascades: Autocrine Stimulation.- 4. Prenylation of RAS and Inhibitors of Prenyltransferases.- I. Introduction.- II. C-Terminal Modification of RAS Proteins.- III. Farnesyltransferase and Geranylgeranyltransferases.- IV. Mutational Analyses of Prenyltransferases.- V. Inhibitors of Prenylation.- VI. Biological Effects of Prenyltransferase Inhibitors.- 5. Mammals II: Downstream of RAS and Actin-Cytoskeleton.- I. RAS GAPs.- II. Oncogenic Mutations of RAS.- III. Effectors of RAS.- IV. Actin-Cytoskeleton.- V. G Proteins in the Rho Family (Rho, Rac and CDC42).- VI. RAS-Activated or -Repressed Genes.- 6. From RAS to MAPK: Cell-Free Assay System for RAS- and Rap 1-Dependent B-Raf Activation.- I. Introduction.- II. Cell-free Assay System for the RAS-dependent Activation of the MAP Kinase Cascade in Xenopus Oocyte Cytosol.- III. REKS.- IV. Raf Activation.- V. Conclusion.