But taken together, they can make a difference and they send a signal that we are serious about changing how government operates,"

VOA: standard.2009.04.20

When they receive the signal they make - they change in a very specific way and the cell can recognize this change that's occurred at the cell surface.

当它们接收到信号之后,就会发生十分特殊的变化,细胞能够识别自身表面发生的这种变化

耶鲁公开课 - 生物医学工程探索课程节选