Cells constantly adjust their metabolism based upon available nutrients. They regulate their repairs and transitions through the cell life cycle based upon accessible supplies, requisitioning specific compounds through the cellular communication network as needed.
In a multicellular context, individual cells transform, reproduce, or even commit programmed suicide (apoptosis), to benefit the survival prospects of the whole organism. Dying cells interact with their neighbors, apprising them of their situation. They can send signals for other cells to proliferate and tell cells from afar that it is time for them to die too.
During development, certain cells must surrender their lives to advance an organism to the next stage. Fingers emerge from paddle-shaped hands by apoptosis of the cells that form the webbing between digits-to-be. Such self-sacrifice is the ultimate expression of intercellular cooperation.
Cell-to-cell communication plays critical roles in specifying cell fate and coordinating development in all multicellular organisms. ~ Chinese molecular biologist Xianfeng Morgan Xu