Fig. 1. Signaling kinases and targets that are currently considered to be involved in helium preconditioning. Evidence from experimental studies mainly focuses on signaling cascades induced by early preconditioning; regarding late preconditioning and postconditioning, we have only little data and this needs further investigation. COX-2 = cyclooxygenase-2; eNOS = endothelial NO synthase; EPC = early preconditioning; ERK = extracellular signal-regulated kinase; GSK3β= glycogen synthase kinase 3β; KATP= mitochondrial adenosine triphosphate-regulated potassium channel; LPC = late preconditioning; mKCa= mitochondrial calcium-sensitive potassium channel; mPTP = mitochondrial permeability transition pore; p70s6K = 70-kDa ribosomal protein s6 kinase; PI3K = phosphatidylinositol 3-kinase; PostC = postconditioning; ROS = reactive oxygen species.