中文摘要：

表皮是人体的第一道防护屏障，对维持机体内环境的稳定起到了巨大的作用。表皮是新陈代谢频率较快的组织，正常机体中表皮的增殖、分化和凋亡处于一神动态的平衡中，一旦这种平衡失调，将会导致严重的皮肤病，因此，机体内应有一套精密的调控系统来调控这一过程。Notch、TGF-β和钙离子等信号通路可能参与了表皮的分化。

英文摘要：

The epidermis constitutes the outer layer of the skin and acts as a protective barrier between the body and the environment. Skin undergoes fast self-renewal throughout life to maintain the homeostasis of body＇s internal environment. Its proliferation, differentiation and apoptosis stay in. a dynamic balance. If the balance is broken, it will result in skin diseases, so the body should have a complex and exact control system to regulate this process. Recent advances suggests that several signaling pathways are associated with epidermal terminally differentiated keratinoeytes.