p38 MAP kinase phosphorylation in cytoplasts.

Freshly isolated cytoplasts or fresh PMNs were treated for 10 minutes with control medium or with 20 ng/mL TNF-α. Thereafter, whole cell lysates were prepared and subjected to SDS-PAGE. Western blot was performed with monoclonal Abs that specifically recognized the phosphorylated form of p38 (top panel). Reprobing with anti–total p38 monoclonal Abs (bottom panel), which recognizes p38 regardless of its phosphorylation state, gives an estimation of the equal protein loading. Results are representative of 4 independent experiments.