By enhancing antioxidant defense and reducing oxidative stress in the biliary epithelium, cysteine potentially mitigates damage that could lead to tumorigenesis.[52] Additionally, cysteine contributes to immune regulation by maintaining immune homeostasis, thereby reducing the tumor risk.[53] Conversely, serum lysine levels were positively associated with the risk of BTEBD, possibly due to its role in promoting cell growth and proliferation through the mammalian target of rapamycin signaling pathway. The gene discussed is MTOR; the disease is neoplasm.