PHGDH and neoplasm: These cells are not able to upregulate crucial genes from the serine biosynthesis pathway (SBP), such as phosphoglycerate dehydrogenase (PHGDH) and phosphoserine aminotransferase 1 (PSAT1), making them dependent on serine released by tumour-infiltrating nerves to the microenvironment (Banh et al., 2020).