Recently, the receptor for epidermal growth factor (EGF) was identified as
a downstream element in different signaling pathways. This expanded its cla
ssical function as a receptor for EGF-like ligands to a role as mediator of
diverse signaling systems and as a switch point of a cellular communicatio
n network. In addition, several downstream targets, (e.g. Smad proteins and
STATs) into which signals from synergistic and antagonistic signaling path
ways converge, were identified.