MAP3K4/MEKK4

MAP3K4 (MEKK4, MTK1) is a large STE11-group MAP3K that activates both JNK and p38 via MKK4/7 and MKK3/6. MEKK4 is uniquely coupled to cytoskeletal dynamics: microtubule-depolymerizing agents and the GADD45-MEKK4 complex trigger its activation, and an N-terminal proline-rich region mediates interactions with cytoskeletal regulators. Beyond stress signaling, MEKK4 is essential in development, controlling testis determination and neural-tube closure in mice; mutations underlie the classic Small eye phenotype. In humans, MAP3K4 variants have been linked to disorders of sex development. Recombinant MEKK4 serves studies of GADD45-dependent activation and MAPK cross-talk with the cytoskeleton.