MAP2K4 and neoplasm: To determine whether differential up-regulation of JNK signaling contributes to the observed sexual disparity in tumor size, we manipulated JNK activity by silencing its components such as basket (bsk), TGF-β activated kinase 1 (Tak1), and hemipterous (hep), the JNK kinase (JNKK) in Drosophila (41).