LPS induces phosphorylation of Elk-1 in THP-1 cells.

(A) THP-1 cells were stimulated with LPS (10 μ/mL) for 0 to 25 minutes. Cytoplasmic extracts were prepared, and proteins were separated by SDS-PAGE. Western blot analysis was performed using antibodies against either phosphorylated or nonphosphorylated ERK1/2. (B) THP-1 cells were stimulated with LPS (10 μg/mL) for 0 to 60 minutes. Nuclear extracts were prepared, and proteins were separated by SDS-PAGE. Western blot analysis was performed using antibodies against phosphorylated Elk-1. (C) Nuclear extracts from LPS-stimulated THP-1 cells (0-60 minutes) were incubated with oligonucleotides containing SRE4 or Sp1 and protein-DNA complexes analyzed by EMSAs. (D) THP-1 cells were LPS-stimulated (15 minutes) with or without PD98059. Nuclear extracts were incubated with SRE4, and complexes were analyzed by EMSAs.