The upregulated phosphorylation of MEK1 was reported to stimulate the syntheses of TLR2 and surfactant protein-A (SP-A) in human alveolar epithelial A549 cells (Wu et al., 2011), where TLR2 existed in human pulmonary epithelial cells and participated in the response to lung injury (Droemann et al., 2003; Slevogt et al., 2008), and SP-A could help the lungs defend bacterial infections (LeVine et al., 2000). This evidence concerns the gene MAP2K1 and bacterial infectious disease.