In WT pups, NEC was associated with increased expression of pro-inflammatory genes in the jejunum and ileum compared to WT dam-fed mice (Fig. 1, box Mediators of inflammation), with up to sixfold increases in Il6 (Fig. 3a), Il1b (Supplementary Fig. 3a), and C-X-C motif chemokine ligand 1 (Cxcl1; Fig. 3b). This evidence concerns the gene IL1B and necrotizing enterocolitis.