In order to survive and perform their functions, cells need to respond to many extracellular signals such as mitogens, hormones, cytokines, physical changes of the environment and stress. These extracellular signals induce various distinct cellular processes, which are largely executed by induction of denovo gene expression. Most of the extracellular agents cannot penetrate the cells, and bind to membranal receptors in order to activate transcription. The extracellular signals are transferred from the membranes to the genes in the nucleus via several communication lines known as intracellular signaling pathways, which operate within a complex network.
In many cases, the transmission of signals through these pathways involves sequential phosphorylation events by protein kinases, which are termed kinase cascades. Such a mechanism is used by four mitogen-activated protein kinase (MAPK) signaling cascades and the PI3K/AKT pathway, which are important in the transmission of many extracellular signals.
Our current studies focus on the mechanism by which the linear signaling cascades induce many distinct and even opposing physiological and pathological processes, which include proliferation, differentiation, angiogenesis, stress response, survival, apoptosis, developmental diseases and cancer.