MAP4K4 (Mitogen-activated protein kinase kinase kinase kinase 4) belongs to the serine threonine protein kinase family and specifically activates MAPK8 JNK. It may play a role in the response to environmental stress and is thought to function through the MAP3K7-MAP2K4-MAP2K7 kinase cascade, and mediate the TNF alpha signaling pathway. It interacts with the SH3 domain of the adapter protein Nck. MAP4K4-dependent signaling inhibits PPARG responsive gene expression, adipogenesis, and insulin stimulated glucose transport.