MLK

Mixed-lineage kinases MLK1, MLK2, MLK3, and MLK4 are TKL-group MAP3Ks defined by an SH3 domain, a Cdc42/Rac-interaction CRIB motif, and dual leucine zippers. Binding of active Rho-family GTPases relieves autoinhibition, letting MLKs phosphorylate MKK4 and MKK7, which in turn activate JNK; this pathway couples cytoskeletal and stress inputs to apoptosis, inflammation, and neuronal death. MLK3 (MAP3K11) also influences inflammasome and metabolic signaling, and family members are studied in Parkinson's disease models and in cancer cell survival. Selective MLK3 inhibitors show neuroprotective promise. Recombinant MLKs support JNK-cascade reconstitution and inhibitor screening.