TI  -  <prot>JNK1</prot> : a protein kinase stimulated by UV light and <prot>Ha-Ras</prot> that binds and
      phosphorylates the  <prot>c-Jun</prot>  activation domain.
PG  - 1025-37
AB  - The ultraviolet (UV) response of mammalian cells is characterized by a
      rapid and selective increase in gene expression mediated by <prot>AP-1</prot> and
      <prot>NF-kappa B</prot>. The effect on <prot>AP-1</prot> transcriptional activity results, in part,
      from enhanced phosphorylation of the <prot>c-Jun</prot> NH2-terminal activation domain.
      Here, we describe the molecular cloning and characterization of <prot>JNK1</prot>, a
      distant relative of the <prot>MAP kinase</prot> group that is activated by dual
      phosphorylation at Thr and Tyr during the UV response. Significantly,
       <prot>Ha-Ras</prot>  partially activates  <prot>JNK1</prot>  and potentiates the activation caused by
      UV.  <prot>JNK1</prot>  binds to the  <prot>c-Jun</prot>  transactivation domain and phosphorylates it
      on Ser-63 and Ser-73. Thus, <prot>JNK1</prot> is a component of a novel signal
      transduction pathway that is activated by oncoproteins and UV irradiation.
      These properties indicate that <prot>JNK1</prot> activation may play an important role
      in tumor promotion.
AD  - Howard Hughes Medical Institute, Department of Biochemistry and Molecular
