PHGDH and cancer: Also, enzymes implicated in serine biosynthesis, such as phosphoglycerate dehydrogenase (PHGDH), are upregulated in triple-negative breast cancer and melanoma8,9, while serine hydroxymethyltransferase 2 (SHMT2) expression and glycine consumption correlate with cancer cell proliferation and poor prognosis across several cancer cell types10–12.