ABSTRACT
Basal signal transduction systems are usually involved in transducing extracellular signals into the intracellular environment and conveying the message to the site where the information is translated by converting the signal into an action. Components of the major stress defense systems are constitutively present to maintain cellular homeostasis and to contribute to cellular processes, such as growth, proliferation, and apoptosis. The mitogen-activated protein kinase (MAPK) cascade plays an integral role in the transduction of signals from both stress and mitogen stimuli, such as growth factors and hormones, culminating in the phosphorylation of nuclear factors and the transcriptional activation of downstream genes. The MAPK cascade consists of multiple pathways, which affect each other through various combinations. In higher animals, there are pathways that predominantly transduce either stress or mitogenic signals promoting cell proliferation. The classical MAPK pathway is stimulated by growth factors, cytokines, tumor necrosis factor-α, and hormones through activation of receptor tyrosi.
