The 4 AA formulation specifically targets DMT1. Eight-week-old male mice (n = 10) were fed a low-iron diet for 10 days. Subsequently, mice were fasted for 2 hours and then administered an electrolyte buffer with or without the 4 AAs by oral, intragastric gavage. One hour later, mice were killed, and BBMVs were isolated from duodenal scrapes for DMT1 western blots (A). DMT1 protein levels were higher in the 4 AA group (*P < .05; unpaired t test) (B). Another group of 10 mice was treated identically, and duodenal scrapes were used to isolate total membrane proteins for FPN1 western blots (C). FPN1 expression was unaffected by the 4 AAs (unpaired t test) (D). To demonstrate specificity, another group of iron-deprived mice (n = 5) was also treated with a formulation made up of 5 AAs that did not increase DMT1 protein expression in loop studies (or buffer only; n = 5). Outcomes showed that the 5 AAs did not increase DMT1 protein levels in BBMVs (unpaired t test) (E-F).