ABSTRACT
The mechanism by which eukaryotic cells regulate their proliferation remains a mystery. The discovery that the B subunit induces opposite effects on the growth of the same 3T3 fibroblasts, depending on the cell’s state of growth, raised the possibility that endogenous gangliosides may play a fundamental role as bimodal regulators of cell growth. Understanding the mechanism of action of proliferative stimuli requires the identification of the intracellular signals responsible for the initiation or modulation of the proliferative response. The activation of cellular protein kinases appears to be a key event in the regulation of cell growth. A number of growth factor receptors and retroviral oncogene products exhibit tyrosine kinase activity. A number of growth factor receptors and retroviral oncogene products exhibit tyrosine kinase activity.
