MLK3 or Mixed-Lineage Kinase 3 is a mitogen-activated protein kinase kinase kinase capable of preferentially activating MAPK8/JNK kinase and functions as a positive regulator of JNK signaling pathway. MLK3 can directly phosphorylate and activate IkappaB kinase alpha and beta, and is found to be involved in the transcription activity of NF-kappaB mediated by Rho family GTPases and CDC42. MLK3 is a signal-integrating kinase with conventional MAP3K catalytic activity and additional noncatalytic functions that contribute to RAF/ERK signalling. MLK3 is a component of the BRAF/RAF1 complex and is required for integrity of the complex and for activation of ERK by the complex.
