FIGURE 2.

Specificity of anti-phospho-p38 antibodies. A, dot blots of immobilized p38 peptides were immunoblotted (IB) with the antibodies recognizing p38 phosphorylated (P) on Thr-180 (9211) or Tyr-182 (P-Tyr). B, immunoblots of phosphorylated activation loop mutants of p38α. Kinase-dead GST-p38 (K53M) and the indicated activation loop mutants, either left untreated or phosphorylated on available activation loop phosphoacceptor sites by MKK6, were immunoblotted as in A (upper two panels) and with antibodies recognizing total p38 (lowest panel).