RBP4 and necrotizing enterocolitis: Multiple apolipoproteins, including APOA4, APOC2, APOE, APOD, APOC3, ApoN, and proteins related to lipoprotein metabolism (PON1, SAA, RBP4, Transthyretin, PCKS9, PAF-AH, and PLTP) were affected in abundance in response to increasing NEC score.