JNK and cJun activation in NPM-ALK⁺ ALCL tumors. (A) JNK and cJun phosphorylation were assessed in 22 ALK⁺ ALCL tumors using immunohistochemistry and a tissue microarray. Using a 10% cutoff, nuclear expression of p-JNK was found in 15 (68%) ALK⁺ ALCL, with most tumor cells being positive in the p-JNK⁺ group of tumors. cJun was expressed and was phosphorylated at serine 73 in a variable proportion of tumor cells, in accordance with our recently published data.³⁰  Double immunostaining confirmed the coexpression of CD30 and p-JNK in tumor cells (inset: red, membranous CD30 expression; dark brown, nuclear p-JNK expression). (B) The median percentage of cJun⁺ tumor cells in ALK⁺ ALCL was significantly higher in tumors expressing p-JNK than in tumors negative for p-JNK (box and whisker plot). The boxes indicate percentages of cJun⁺ tumor cells between 25%-75%. The bars indicate percentages of cJun⁺ tumor cells between 5%-95%.