When a growth factor and its receptor bind together, the receptor can either transiently exert its kinase activity or form a complex with an intracellular tyrosine or serine/threonine kinase. Subsequently, the activated receptors result in the activation of other proteins in the signaling pathway and the production of various second messengers. These signals are finally transmitted into the nucleus and induce the expression of specific genes.
Fig 1. Growth Factor Signal Transduction