MAP4K4 (Mitogen-Activated Protein Kinase Kinase Kinase Kinase 4), also known as HGK (hepatocyte growth factor-regulated kinase), is a member of the MAP kinase kinase kinase kinase family. It consists of a kinase domain and a CNH domain, primarily located in the cytoplasm. MAP4K4 plays a crucial role in regulating cell migration, apoptosis, and inflammation, affecting cell stress response and immune response by activating the JNK and NF-κB signaling pathways. The expression of MAP4K4 is specific in different tissues and cells, and mutations or dysregulation in its gene expression are associated with cardiovascular diseases, diabetes, and cancer.