MAPK9 and breast carcinoma: Other studies have used the JNK inhibitor, SP600125, to pharmacologically inhibit JNK activity to implicate this pathway in breast cancer cell models.13, 14 Studies carried out in the MCF‐7 breast cancer cell line have shown that the JNK pathway is required for cell death in response to UV15 and taxol16 and also for MCF‐7 proliferation and cell cycle progression.15 Given the selectivity issues of SP600125, the roles attributed to JNK1 and JNK2 remain unclear, therefore JNK as a target in this context needs to be investigated further using more selective tools.