MAPK8 and breast carcinoma: To confirm regulation of IL-1 by JNK in breast cancer cells, we measured IL1A/B mRNA and secreted protein levels upon expression of a constitutively active form of JNK, consisting of a protein fusion between JNK1 and its upstream MAPK kinase (MAPKK) activator MKK7 (MKK7-JNK), or a mutated version (MKK7-JNK(mut)), in which the phosphorylation motif Thr180-Pro-Tyr182 in JNK1 has been replaced with Ala-Pro-Phe, thereby preventing its activation by MKK7 (refs. 19,20).