Influence of metabolized clarithromycin, M-4, on MAPKs activation in NPFs after LPS stimulation. NPFs at a concentration of 5 × 105 cells/ml were stimulated 1.0 μg/ml LPS in the presence of various concentrations of M-4. After 4 hours, MAPKs activation was assayed by ELISA. Data are the mean ± SE of five different subjects. A, p38 MAPK; B, ERK1/2; C, JNK. MAPKs, mitogen-activated kinases; NPFs, nasal polyp fibroblasts; LPS, lipopolysaccharide; ELISA, enzyme-linked immunosorbent assay; NS, not significant (P > 0.05).