INSIG1 and steatosis: Using our imaging data to identify in vivo drivers of steatosis, we observed that knockout of Insig1, the growth inhibitor Pten86, the ISR inhibitor Eif2α (Eif2s1), and the alanine-tRNA synthetase Aars all caused steatosis, as measured by enlargement and signal increase of lipid droplets (Figures 7G, 7H).