Western blot analysis of human IGF1 was performed by loading the indicated amounts of recombinant human IGF1 protein per well onto a 4-20% Tris-HCl polyacrylamide gel. Proteins were transferred to a PVDF membrane and blocked with StartingBlock (TBS) Blocking Buffer (Product # 37542) for at least 1 hour. The membrane was probed with an IGF1 polyclonal antibody (Product # PA1-130) at a concentration of 1 µg/mL overnight at 4C on a rocking platform, washed in TBS-0.1%Tween-20, and probed with a goat anti-rabbit IgG-HRP secondary antibody (Product # 31460) at a dilution of 1:10000 for at least 1 hour. Chemiluminescent detection was performed using SuperSignal West Pico (Product # 34080).