Intestinal enterocyte‒specific Rnf217 knockout mice have increased FPN in the intestinal epithelium and increased iron absorption. (A) RT-PCR analysis of Rnf217 mRNA measured in the small intestine of control (Rnf217^flox/flox) and Rnf217^{Villin/Villin} mice (n = 5 mice per group). (B-C) Hepatic and duodenum nonheme iron concentration was measured in 2-month-old and 6-month-old Rnf217^flox/flox and Rnf217^{Villin/Villin} mice (n = 5-6 mice per group). (D) Enhanced DAB iron staining of duodenum and liver sections, and (E) FPN immunostaining staining of duodenum sections obtained from Rnf217^flox/flox and Rnf217^{Villin/Villin} mice at the indicated ages (n = 4 mice per group). (F) Nonheme iron concentration was measured in the duodenum and liver of HID-fed Rnf217^flox/flox and Rnf217^{Villin/Villin} mice (n = 8-9 mice per group). (G) Perls’ Prussian blue staining of duodenum and liver sections, and (H) FPN immunostaining of duodenum sections obtained from HID-fed Rnf217^flox/flox and Rnf217^{Villin/Villin} mice (n = 4 mice per group). Scale bars, 100 μm (D-E,G,H). *P < .05 and **P < .01 (Student t test).