Reduction of AKT-mTOR signaling in high-altitude placentas. A) Proteins were extracted from nonlabored elective Caesarean placentas at both sea level and 3100 m. Western blot analysis was used to measure phosphorylated and total protein levels of P-AKT (Ser473), P-AKT (Thr308), AKT, P-TSC2 (Thr1462), TSC2, P-4E-BP1 (Ser65), P-4E-BP1 (Thr37/46), and 4E-BP-1. β-Actin was used as a loading control. B) Densitometric quantification of band intensity. Levels of phosphorylated and total protein are presented as a ratio to the sea-level control (100%). Data are means ± se from all 24 samples. *P < 0.05; **P < 0.01. C) No change in 4E-BP1 transcript level. qRT-PCR was used to measure the 4E-BP1 mRNA level by TaqMan; 18S was used as a house-keeping gene.