The calcium signal and the regulation of ErbB receptors

The activation of tyrosine kinase receptors of the ErbB family, implicated
in cell proliferation, generate a transient increase in the concentration
of cytosolic free Ca2+. The cell uses this early signal to downregulate the
activity of these receptors, and their downstream signalling pathways, to
avoid an hyperproliferative response. Calmodulin, an intracellular Ca2+
sensor, intervenes in this process. We shall describe the mechanisms
responsible for the generation of the Ca2+ signal, and the action that the
Ca2+/calmodulin complex exerts on ErbB1/EGFR and ErbB receptors, and the
adaptor protein Grb7. This adaptor protein regulates cell migration, and it
is an important downstream component of ErbB receptors-initiated signalling
pathways.