Meaning of signal molecule in English:
signal molecule
noun
Any extracellular or intracellular molecule (e.g. a hormone, neurotransmitter, second messenger, etc.), released in response to a stimulus that promotes a particular reaction in a cell, or behaviour in an organism; especially such a molecule involved in cell-to-cell communication.
Origin
1960s; earliest use found in Journal Insect Physiology.
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