PHGDH and neoplasm: Further assessment for “clinically relevant features” in a subset of 251 samples pointed to additional associations between enzymatic PHGDH and PSAT1 expression and several recognized risk features, including estrogen and progesterone receptor negative status, mutated p53, higher tumor grade, heightened expression of the cell proliferation markers PCNA and Ki-67, and higher levels of ERBB2 [23].