HK2 and neoplasm: For example, YY1 activates Hexokinase 2 (HK2)/pyruvate dehydrogenase kinase-1 (PDK1) to promote glycolysis, so that tumor cells generate excessive lactic acid, and impairs T cell function, expands regulatory T cells, and fosters an immunosuppressive microenvironment, thereby enhancing tumor cell resistance to both chemotherapy and immunotherapy.