The Regulation of gene expression -- The regulation of enzyme activity -- Function and structure of signaling pathways -- Signaling by nuclear receptors -- G-protein coupled signal transmission pathways -- Intracellular messenger substances: "Second Messengers" -- Ser/Thr-specific protein kinases and protein phosphatases -- Signal transmission via transmembrane receptors with tyrosine-specific protein kinase activity -- Signal transmission via ras proteins -- Intracellular signal transduction: The protein cascades of the MAP kinase pathways -- Membrane receptors with associated tyrosine kinase activity -- Other receptor classes -- Regulation of the cell cycle -- Malfunction of signaling pathways and tumorigenesis: Oncogenes and tumor suppressor genes -- Apoptosis -- Ion Channels and signal transduction