PHGDH and neoplasm: Figure 3 illustrates that both glucose and glutamine are required for the de novo serine/glycine synthesis pathway. Several chemotherapeutic agents target this pathway, underscoring the significance of serine, glycine and one-carbon metabolism for tumor progression [41]. In this study, we identified the de novo serine synthesis pathway as a potential target for apoA-I anti-neoplastic activity. Phgdh, the gene encoding the first enzyme of this pathway, was the most repressed transcript in tumors recovered from A-I Tg+/– mice relative to A-I KO mice (Table 1B and Supplementary Table 2).