The Ca2+/calmodulin-dependent protein kinases (CaM kinases) comprise a structurally related subfamily of serine/threonine kinases which include CaMKI, CaMKII and CaMKIV. CaMKII is an ubiquitously expressed serine/threonine protein kinase that is activated by Ca2+ and calmodulin (CaM) and has been implicated in regulation of the cell cycle and transcription. There are four CaMKII isozymes, designated alpha, beta, gamma and delta, which may or may not be co-expressed in the same tissue type. CaMKIIalpha is autophosphorylated on Thr 286 upon the binding of the Ca2+/CaM complex to the autoinhibitory domain of CaMKII. This process is called Ca2+/CaM trapping, which is thought to be involved in the synaptic encoding of information.