Our analysis not only provides the most comprehensive map of the tryptophan modifications to date, spanning nearly the full depth of the tryptophan modifications, but also highlights the predominant role of oxidative modifications in hemoglobin (HBB) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), mainly associated with tumor hypoxia. The gene discussed is GAPDH; the disease is neoplasm.