PHGDH and cancer: Using data from the Cancer Cell Line Encyclopedia (CCLE) (Barretina et al., 2012) and our own qPCR and western blots, we found that breast cancer cell lines robustly maintain the low-PSAT1 phenotype of luminal tumors, while the differences in PHGDH and PSPH were less pronounced or absent (Figures 1I-1L and S1C-S1H).