... 2–3 and 4– 5). Notably, JSP1 seemed to stimulate preferentially the phosphorylation of the p46 isoform of JNK,whereas sorbitol treatment induced phosphorylation of both the p46 and p55 isoforms. ... necessary for the intrinsic phosphatase activity of the enzyme. However,myristoylation determined the subcellular localization of JSP1, and was required for JSP1-induced activation of the JNK ... determine whether inhibition of JNKabrogated the effect despite JSP1 expression. However,these efforts were frustrated by the lack of specificity of SP600125, which has also been reported by others[42,43]....