Positive mediators of cell proliferation in Neoplasia: Growth factors and receptors

Complex signaling networks underlie the regulation of fundamental processes such as embryonic development, tissue differentiation, and systemic responses to wounds and infections. Among the major mediators of these events, growth factors are in large part responsible for the control of cell proliferation, differentiation, and survival. The specific interaction of a growth factor with its receptor initiates a cascade of intracellular biochemical reactions that ultimately mediate the biological response in the target cells. The cytoplasmic molecules that participate in these pathways have been termed second messengers-their activation allows the transmission of the signals to the nucleus and eventually the regulation of the expression of genes involved in mitogenic and differentiation responses.