The bacteria–epithelial cell coculture in our NEC-on-a-Chip model resulted in increased expression of proinflammatory cytokines IL1B and IL8 (Figure 2, E and H), as well as decreased expression of proliferation markers Ki67 and PCNA (Figure 2, F and I) at both 24 and 72 hours after inoculation compared with control chips. The gene discussed is PCNA; the disease is necrotizing enterocolitis.