The MAPK family includes several subgroups encompassing the extracellular signal-regulated kinase (ERK) family, the p38 Map kinase family, and c-Jun NH2-terminal kinase (JNK) family. JNK kinase group includes 3 members, JNK1, JNK2, and JNK3. JNK kinases are phosphorylated in response to various activations by environmental stress and pro-inflammatory cytokines by phosphorylating a number of transcription factors, primarily components of AP-1 such as c-Jun and ATF2 and thus regulate AP-1 transcriptional activity. JNK kinases are characterized by requirement for dual phosphorylation at a T-P-Y motif for enzymatic activation. The Poly6331 antibody has been shown to be useful for western blotting, immunoprecipitation, and immunohistochemistry of human, mouse, and rat JNK1 p46 and JNK1 p54 protein.