Prologue: Signal Transduction, origins and ancestors -- First messengers -- Receptors -- GTP-binding proteins and signal transduction -- Effector enzymes coupled to GTP binding proteins: adenylyl cyclase and phospholipase C -- The regulation of visual transduction and olfaction -- Intracellular calcium -- Calcium effectors -- Phosphorylation and dephosphorylation: protein kinases A and C -- Nuclear receptors -- Growth Factors: Setting the framework -- Signalling pathways operated by receptor protein tyrosine kinases -- Signal transduction to and from adhesion molecules -- Adhesion molecules in the regulation of cell differentiation: Mainly about Wnt -- Activation of the innate immune system: the Toll-like receptor 4 and Signalling through Ubiquitylation -- Traffic of white blood cells -- Tyrosine protein kinases and adaptive immunity : TCR, BCR, soluble tyrosine kinases and NFAT -- Phosphoinositide 3-kinases, protein kinase B and signalling through the insulin receptor -- Protein Kinase C revisited -- Signalling through receptor serine/threonine kinases -- Protein dephosphorylation and protein phosphorylation -- Notch -- Targeting transduction pathways for research and medical intervention -- Protein domains and signal transduction.