Mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4), also known as hepatocyte progenitor kinase-like/germinal center kinase-like kinase (HGK) and Nck-interacting kinase (NIK), is a serine/threonine (S/T) kinase. To date, MAP4K4 has been found to be expressed in all tissue types with a relatively more pronounced expression in the brain and testes. It is involved in a wide array of physiological processes including cell migration, proliferation and adhesion. Its activity has been implicated in systemic inflammation, metabolic disorders, cardiovascular disease and cancer.