PHGDH and neoplasm: Analysis of the serine and glycine levels in the tumours from these mice mirrored the results from the plasma, showing either PH755 treatment or -SG diet lowered intra-tumoral serine and glycine levels (Fig. 7e and Supplementary Figure 7d), although in each case the -SG diet was more effective in lowering intra-tumoral serine and glycine levels that treatment with the PHGDH inhibitor.