Infrequently, CD97 is associated with regulation of the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) and phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathways, either in normal settings [42,47] or in experimental cancer studies. The gene discussed is ADGRE5; the disease is cancer.