As AMPK-mediated PD-L1 phosphorylation leads to its abnormal glycosylation and degradation, metformin, an AMPK activator, phosphorylates PD-L1 at S195, decreases the stability and membrane localization of PD-L1, and enhances cytotoxic T lymphocyte activity against cancer cells [29]. The gene discussed is CD274; the disease is cancer.