The insulin/IGF-like signaling (IIS) and TOR pathways are responsible for conveying nutrient signals and regulating growth in Drosophila. Activation of the IIS pathway occurs when insulin-like peptides bind the insulin receptor. Activation of the TOR signaling pathway occurs in the presence of amino acids via an unknown mechanism.
Together, these pathways coordinate cell-autonomous and non cell-autonomous growth responses to nutrients. The exact way these two signaling pathways are coordinated and their outputs balanced are not understood.