Figure 1.

The dFOXO protein mediates a transcriptional response to insulin signaling. Under conditions of abundant nutrients, dFOXO is retained in an inactive state in the cytoplasm due to phosphorylation by Akt. When insulin levels fall, dFOXO is dephosphorylated and translocated into the nucleus, where it stimulates transcription of 4E-BP and presumably other negative regulators of growth. In addition, active dFOXO increases expression of the insulin receptor gene [4], which may result in increased insulin sensitivity under low insulin conditions.