refers to something that is constantly undergoing change or something that is likely to undergo change. Biochemically this is an important concept as far as kinetics is concerned in metalloproteins. This can allow for the rapid synthesis and degradation of substrates in biological systems. Biologically, labile cells refers to cells that constantly divide by entering and remaining in the cell cycle. An important example of this is in the epithelium of the cornea, where cells divide at the basal level and move upwards and the top most cells die and fall off. In medicine, the term "labile" means susceptible to alteration or destruction. For example, a heat-labile protein is one that can be changed or destroyed at high temperatures. The opposite of labile in this context is "stable."