Ndfip1 is important for regulating DMT1 under iron-deficient conditions in vivo. DMT1 expression in the duodenum of (A) Ndfip1^+/+ mice and (B) Ndfip1^−/− mice fed a low iron diet for 3 weeks. DMT1 levels are increased in Ndfip1^−/− mice compared with Ndfip1^+/+ mice. Scale bar, 50 μm. (C) DMT1 relative transport activity in enterocytes isolated from Ndfip1^+/+ and Ndfip1^−/− mice fed a low iron diet. DMT1 activity is increased in Ndfip1^−/− mice compared with Ndfip1^+/+ mice. Data represented as mean ± SD,*P < .05, n = 3-7.