This review is intended to focus on the currently known roles of protein kinase A (PKA), Ca2+-calmodulin-dependent protein kinase (CaMK), protein kinase C (PKC), phosphoinositide 3-kinase (PI3K) and mitogen-activation protein kinase (MAPK), in cardioprotection against ischemia-reperfusion (I/R) injury as well as in a number of cardiac diseases. The gene discussed is CAMK2G; the disease is heart disorder.