The potential role of the heme oxygenase-1 pathway and downstream effectors in the compensatory response to repeated ischemia-reperfusion injury and hemolytic stress in sickle cell disease. Red text represents up-regulated genes or molecules measured in this study in sickle cell patients. CO indicates carbon monoxide; cGMP, cyclic guanosine monophosphate; p38MAPK, p38 mitogen-activated protein kinase; p21, a cyclin-dependent kinase inhibitor.