When a certain enzyme is activated inside cells, ATP gets converted into a molecule called cyclic AMP, and cyclic AMP is an example of one of these molecules called second messengers.

细胞内的某种酶被激活后,ATP就能转化为一种叫cAMP的分子,cAMP是一种第二信使分子的范例

耶鲁公开课 - 生物医学工程探索课程节选