Fig 3.

Lower insulin-like growth factor 1 (IGF1) concentrations in livers and plasma of Arfrp1^liv−/− mice. (A) Igf1 mRNA expression determined by qRT-PCR from livers of Arfrp1^liv−/− and control mice. IGF1 protein in plasma and livers of Arfrp1^liv−/− and control mice was detected by ELISA. (B) IGFBP2 protein in plasma of Arfrp1^liv−/− and control mice was detected by ELISA. Igfbp2 mRNA was determined by qRT-PCR. (C) Downregulation of Arfrp1 by siRNA in primary hepatocytes was verified by qRT-PCR and Western blotting. Igf1 and Igfbp2 mRNAs were determined by qRT-PCR. Secreted IGF1 from primary hepatocytes was detected by ELISA. (D) Measurement of IGF1 secretion and Igf1 mRNA from primary hepatocytes after siRNA-mediated downregulation of Rab6. (E) Attenuated growth retardation of Arfrp1^liv−/− mice after treatment with IGF1. Body weight and composition were determined at the age of 5 weeks. Arfrp1^liv−/− mice received a daily injection of IGF1 from the age of 2 weeks; control mice were exposed to saline. *, P < 0.05; **, P < 0.01; ***, P < 0.001.