Previous studies have indicated the critical role of serine in regulating cell proliferation, and inhibition of endogenous serine synthesis through interfering phosphoglycerate dehydrogenase (PHGDH) or PSAT1 may enhance the anti-tumor effect of extrinsic serine restriction.36,37 However, complete dietary inhibition of serine seems difficult and the effect of serine on tumor metastasis remains largely unclear. This evidence concerns the gene PHGDH and neoplasm.