HK2 and digestive system neoplasm: The expression of HKII isoform is linked to the proliferation of hepatoma cells [85], and its overexpression correlates with poor prognosis in various tumor types, including tumors of the digestive system [82], brain metastases of breast cancer [86], and is indicative of a poor therapeutic response in circulating lung tumor cells expressing high levels of HKII [87].