MAP4K 

MAP kinase kinase kinase kinases (MAP4Ks) belong to the mammalian Ste20-like family of serine/threonine kinases. MAP4Ks including MAP4K1/HPK1, MAP4K2/GCK, MAP4K3/GLK, MAP4K4/HGK, MAP4K5/KHS, and MAP4K6/MINK have been reported to induce JNK activation through activating the MAP3K-MAP2K cascade. MAP4Ks play important roles in the regulation of cell apoptosis, cell survival, cell autophagy, and cell migration. Several studies reported that MAP4Ks are involved in the regulation of immune-cell responses through JNK-independent pathways.

MAP4K1/HPK1 and MAP4K4/HGK play negative roles in T-cell activation and inflammatory responses. In contrast, MAP4K3/GLK plays a positive role in T-cell activation and autoimmune responses. Moreover, MAP4K1 downregulation and MAP4K3 overexpression in T cells are involved in human autoimmune diseases such as psoriatic arthritis, rheumatoid arthritis (RA), adult-onset Still’s disease, and SLE.