However, although there was a very slight increase of the numbers of CD45 cells and neutrophils in Ahr-/- mice compared with wild-type mice at baseline without NEC (Supplementary Fig. 4k, l), the percentage of CD45 cells that were neutrophils did not differ between Ahr-/- mice and wild-type mice at baseline (Supplementary Fig. 4m), and there were also no significant differences on the numbers of CD45 cells, the number of neutrophils, and the percentage of neutrophils in CD45 cells in Ahr-/- compared with wild-type mice with NEC (Supplementary Fig. 4k–m). This evidence concerns the gene AHR and necrotizing enterocolitis.