In addition to the improvement of the tumor blood flow, the Wegiel and Otterbein’ group also reported that CO could induce apoptosis in lung cancers by altering the tumor microenvironment to increase the CD86 expression, and then activating mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinases (Erk) 1/2 pathway [38]. The gene discussed is WNK2; the disease is lung cancer.