Cell-to-cell signaling is important to both multicellular ...

Between the receptor molecule that is activated and signal-transduction pathway that is to be activated there may be a second messenger. Note-The the hormone or signal that attaches the to the receptor site is called the first messenger. The most common secondary messengers include. a. cyclic AMP (cAMP) b. Calcium ions and inositol triphosphate. ................
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