p38 Mitogen-activated protein kinase alpha (p38 MAPKa) is a member of the MAPK family. It is activated by cellular stresses and has a number of cellular substrates whose coordinated regulation mediates inflammatory responses. In addition, it is a useful anti-inflammatory drug target that has a high specificity for Ser-Pro or Thr-Pro motifs in proteins and contains a number of transcription factors as well as protein kinases in its catalog of known substrates.