Furthermore, hub protein networks including downregulated and upregulated DEPs were constructed for the short-term progression of NEC (Fig. 5E, F), revealing that downregulated proteins such as ACTN4, SRC, and KRTDAP were positively correlated with each other, while these proteins were negatively correlated with upregulated proteins such as MMP9, SERPINA5, and ACAN (Supplementary Fig. 3A). Here, MMP9 is linked to necrotizing enterocolitis.