Hcrmone , n nutransmitt cell factors,growth factor from the extraceliular are called the first messenger cAMP, cGMP, W3,DAG,Cain cytoplasm are called the second messengers.

• 胞外第一信使（包括激素、神经递质、细胞因子、生长因子等）与其特异受体结合后，被激活的受体通过刺激特定的效应酶或离子通道，而在胞浆内产生第二信使（包括cAMP，cGMP；IP_3，DAG；Ca~(2+)等）；