Mkk4 and Hemipterous/Mkk7 in TAK1-Mediated Activation of JNK

, potently activates JNK signaling through the activation of the MAPKKK Tak1. gene. Our genetic and biochemical results demonstrate that Mkk4 is dispensable for normal development and host resistance to systemic bacterial infection but plays a non-redundant role as a MAPKK acting in parallel to Hemipterous/Mkk7 in dTAK1-mediated JNK activation upon Eiger and Imd pathway activation. both MAPKKs, Hep/Mkk7 and Mkk4, are required to induce JNK upon TNF or pro-inflammatory stimulation