PHGDH and cancer: It is also well documented that mediators, such as nuclear factor erythroid-2 related factor 2, sirtuin 2 (SIRT2), protein kinase C (PKC) λ/ι, and Tat-interacting protein 60, mediate serine synthesis by upregulating or downregulating the expression of PHGDH or other metabolic genes in various cancer cells [8,[42], [43], [44], [45]].