Maoto inhibits intracellular protein derived from PR8. A549 cells infected with PR8 (moi = 1) were cultured with or without maoto for 24 hr. Proteins derived from PR8 were visualized by labeled mAb. (a) Cells were stained with mAb to M2 or NP (green) and assayed by fluorescence microscopy. Nuclei were dyed blue. (b) Cells were stained with mAb to M2, and fluorescent intensity was assayed by flow cytometry. (c) Cell lysates were assayed by western blot analysis for M2 protein.