CXCR4 and acute respiratory distress syndrome: The possible pathways of Xuebijing's action on ARDS were mainly related with immune cell/cytokine regulating pathways, such as CD4+/CD8+ T cells-related TCR signaling, IL2/IL12-mediated signaling events, p75(NTR)-mediated signaling, CXCR4-mediated signaling events, FAS (CD95) signaling pathway, LPA receptor-mediated events, and immune system.