Growth factors are a kind of substances performing a key function in intercellular communication. They also perform a variety of other biological functions where cellular proliferation is the most important among them, though they directly influence cellular survival, migration, cytodifferentiation and even apoptosis.
The growth factors perform their functions in the liquids and tissues in very low concentrations, in the range of pico - or nanogram. They act by means of attachment to the receptors located on the cellular membrane and transmit an outside signal inside the cell via connections with various phosphorylated protein kinases regulating signaling cascade ultimating in the activation of one or several genes.
Growth factors are a kind of substances dominating in intercellular communication.