IDO1 overexpression in cancers is linked to the inactivation of cancer genes such as Bin1 [29] and p53 [30], BRAF mutations, or abnormal activation of the Mitogen‐Activated Protein Kinase (MAPK) pathway, which triggers Cyclooxygenase‐2 (COX‐2) upregulation, leading to Prostaglandin E2 (PGE2) autocrine release and eventually inducing IDO1 activation via Phosphoinositide 3‐kinase (PI3K) or Protein Kinase C (PKC) signaling pathways [31]. The gene discussed is IDO1; the disease is cancer.