Receptor crosstalk: communication through cell signaling pathways.

The response of cells to extracellular stimuli is mediated in part by a number of intracellular signal transduction pathways. The frequent lack of a one-to-one correlation between receptor activation and intracellular responses, such as predictable nuclear transcription events, is perplexing. This lack of correlation, however, suggests that various signaling pathways intersect and crosstalk to modify and influence the biological outcome of a specific extracellular signal. In this review, the basic pathways and aspects of signal transduction are laid out, and known sites of crosstalk are discussed. A clearer understanding of receptor and cell signaling pathways and levels of crosstalk should provide insight into the paradoxes that underlie both imprecision and predictability in signal transduction.