S100A9 and infection: Flagellin enhanced the expression of the genes encoding β-defensin 4a (DEFB4A), also known as β-defensin 2, peptidase inhibitor 3 (PI3), and calprotectin (S100A8 and S100A9) in HBE cells collected 24 h after initiation of the experiment (infection or control); these flagellin effects were similar in uninfected and MDR-Kpneu-infected HBE cells (Figure 1B).