Molecular mechanism of myocardial conditioning. cGMP, cyclic guanosine monophosphate; ERK, extracellular regulatory kinase; GSK 3beta, glucose synthase kinase 3 beta; GPCR, G-protein-coupled receptor; JAK, Janus kinase signal transducer; mPTP, mitochondrial permeability transition pore; NO, nitric oxide; PKG, protein kinase G; RISK, reperfusion injury salvage kinase; SAFE, survival activating factor enhancement; STAT3, signal transducer and activator of transcription 3; TNF-alpha, tumour necrosis factor-alpha; TNF-R, TNF receptor.