Currently, the concept of cell signal regulation has two basic steps: activation and deactivation. There are many activators of the signals in vivo (e.g., hormones, growth factors, signal cross-talk, etc.). According to the two step theory, cell signals are expected to keep activating, deactivating, activating, deactivating,……However, cell signals in vivo are usually quiescent for the most of the time. This indicates that, there is a mechanism that blocks the signal from being reactivated for a certain period of time after an activation is terminated. Here, we propose that cell’s signal regulation consists of three basic steps: activation, deactivation, and blocking the signal from being reactivated for a certain period of time until cells are ready for a new activation. We explain the third step of regulation using GH/STAT5 and insulin/AKT signal pathways as examples, and discuss why the third step in regulation is important for cell homeostasis and the development of diseases.

目前，细胞信号调节的概念有两个基本步骤：激活和去激活。体内有许多信号的激活剂（例如激素、生长因子、信号串扰等）。根据两步理论，预计细胞信号会保持激活、去激活、激活、去激活……但是，体内的细胞信号通常大部分时间是静止的。这表明，在激活终止后，有一种机制在一定时间内阻止信号被重新激活。在这里，我们提出细胞的信号调节包括三个基本步骤：激活、去激活和阻止信号在一段时间内被重新激活，直到细胞准备好进行新的激活。