PKUMDL-WQ-2201 is a potent and selective non-NAD+-competing allosteric inhibitor of phosphoglycerate dehydrogenase (PHGDH) that selectively inhibits serine synthesis in cancer cells. PKUMDL-WQ-2201 binds to allosteric site II, which is located in the substrate-binding domain. PKUMDL-WQ-2201 inhibits tumor growth of MDA-MB-468 xenografts in mice.