Figure 7. Facilitated Diffusion Model of Ecdysteroid Uptake by Target Cells.
EcI/Oatp74D is required for facilitating cellular uptake of ecdysteroids (blue circles) from the hemolymph into cytoplasm down the concentration gradient. The nuclear receptor complex composed of EcR and Usp regulates the transcription of genes for molting and metamorphosis in the nucleus.