ABSTRACT
In vivo cells are never static. They are constantly altering the expression and
sensitivity of their constituent proteins in maintaining functional, homeostatically
stable internal and external environments. In this regard, changes in the extracellular
milieu can have profound effects on cell function. Under basal physiological
conditions, minor changes in the surrounding environment are quickly sensed and
appropriate homeostatic responses are evoked. However, sometimes the insult to
cells is greater than their ability to respond, leading to abnormal protein expression
profiles. Some pathologies can cause major changes in cellular microenvironments,
and the reaction to these perturbations often invokes a coordinated, interactive
response from many cell types.
