MAP2K4 (mitogen-activated protein kinase kinase 4), also known as MKK4 or JNKK1. is a dual-specificity serine/threonine kinase that functions as a critical component of the MAPK signaling pathway. It directly activates c-Jun N-terminal kinase (JNK) and p38 MAPK by phosphorylating their activation loop residues, mediating cellular responses to stress, apoptosis, differentiation, and inflammation. MAP2K4 antibodies are essential tools for studying its expression, activation status (via phosphorylation at Ser257/Thr261), and interaction partners in various biological contexts. Research has linked MAP2K4 dysregulation to cancer progression, where it may act as a tumor suppressor or context-dependent oncogene. Loss-of-function mutations or reduced expression of MAP2K4 have been reported in multiple cancers, including prostate, pancreatic, and breast cancers. These antibodies are widely used in techniques such as Western blotting, immunohistochemistry, and immunoprecipitation to investigate MAPK pathway dynamics, cellular stress responses, and therapeutic targeting strategies. Some studies also explore its role in metabolic disorders and neurodegenerative diseases. Commercial MAP2K4 antibodies typically target specific epitopes in the kinase domain or regulatory regions, with validation across species and applications being crucial for experimental reliability.