Distinct SERT Function in Feeding and Obesity Figure 5. Western blot analysis of insulin signaling component activity in SERT-deficient mice. A–F. AKT activity in the liver of 3- and 6- month old WT and SERT-deficient mice was evaluated by western blot analysis of AKT Ser473 phosphorylation (pAKT) before and after insulin injection. G–L. IRS1 activity in the liver of 3- and 6-month old WT and SERT-deficient mice was evaluated by western blot analysis of tyrosine- phosphorylated IRS1. IRS1 was first immunoprecipitated with anti-IRS1 antibody (IP-IRS1) and then blotted with anti-IRS1 (IB-IRS1) or anti- PLoS ONE | www.plosone.org 7 March 2012 | Volume 7 | Issue 3 | e32511