Module 2: Figure cell signalling pathways
Summary of the major signalling pathways used by cells to regulate cellular processes.
Cells have a number of signalling systems that are capable of responding either to external stimuli or to internal stimuli. In the case of the former, external stimuli acting on cell-surface receptors are coupled to transducers to relay information into the cell using a number of different signalling pathways (Pathways 1–18). Internal stimuli derived from the endoplasmic reticulum (ER) or from metabolism activate signalling pathways independently of external signals (Pathways 19 and 20). All of these pathways generate an internal messenger that then acts through an internal sensor to stimulate the effectors that bring about different cellular responses. As described in the text, the names of these signalling pathways usually reflect a major component(s) of the pathway.