Iron (pink circle) present in the diet of the fly is transported from the gut lumen into cells that line the gut (orange rectangle). Iron uptake is likely controlled by the Fe(II) transporter Mvl, which is similar to the human iron transporter DMT1. Iron in the cytosol may then be transported across the membranes of the endoplasmic reticulum or Golgi apparatus to the lumen of the secretory pathway: Xiao, Wan et al. have found that a protein called Zip13 is responsible for transporting the iron ions across these membranes. Once in the secretory pathway, the ions can be incorporated into the protein ferritin, which is then secreted into the hemolymph to carry iron to other cells in the fly (Mandilaras et al., 2013).