Role of p38 mitogen-activated protein kinase (MAPK) for vacuole formation in lipopolysaccharide (LPS)-stimulated macrophages

The role of p38 mitogen-activated protein kinase (MAPK) on vacuole formation in lipopolysaccharide (LPS)-stimulaled RAW 264.7 cells was examine. LPS definitely induced the formation of vacuoles in RAW 264.7 cells and SB202190 as a p38 specific inhibitor also induced slight vacuole formation. The simultaneous treatment with LPS and SB202190 induced many more vacuoles in RAW 264.7 cells than the treatment with LPS or SB202190 alone, and the vacuoles were extraordinarily large in size. On the olher hand, an inactive inhibitor of p38 MAPK did not augment LPS-induced vacuole formation. Further, the inhibitors of other MAPKs and nuclear factor (NF)-κB pathways did not affect it. The extraordinarily large vacuoles in RAW 264.7 cells treated wllh LPS and SB202190 were possibly formed via fusion of small vacuoles. However, SB202190 did nol augment vacuole formation in CpG DNA of interferon (IFN)-γ-stimulated RAW 264.7 ceUs. The tole of p38 MAPK in the vacuole formation in LPS-stimulated macrophages is discussed.