PHGDH and neoplasm: The low efficacy of targeting some steps in LAR tumors have been suggested in previous studies.39,40 For example, blocking SPT and CERS have been reported to be ineffective as they inhibit the formation of 1-deoxy(dihydro)ceramides and thus promote tumor growth.39 Besides, serine restriction, especially through PHGDH inhibition, has been proven to be more effective for basal-like rather than non-basal-like tumors,40 which was consistent with our results.