HLA-F and preeclampsia: To evaluate the hypothesis that insufficient HLA-F expression results in the reduced proliferation of trophoblastic cells via the down-regulation of PKM2-mediated glycolysis, we first assessed PKM2 enzyme activity, pyruvate content, and PKM2 protein expression in placental tissues obtained from patients with preeclampsia (n = 12) and normal late pregnancy controls (n = 12).