The mammalian Ste20-like kinase 4 (MST4), also known as STK26. is a serine/threonine kinase belonging to the STE20 protein kinase family. It plays a role in regulating cell signaling, polarity, proliferation, and migration. MST4 antibodies are immunological tools used to detect and study the expression, localization, and function of MST4 in various biological contexts. Structurally, MST4 contains an N-terminal catalytic kinase domain and a C-terminal regulatory region that facilitates interactions with scaffolding proteins, such as STRADα and MO25. forming complexes that influence its activity and subcellular localization, particularly at the Golgi apparatus. MST4 is implicated in pathways like the Hippo signaling cascade and has been linked to cellular responses to stress, apoptosis, and cytoskeletal reorganization. Dysregulation of MST4 has been associated with cancers, inflammatory diseases, and metabolic disorders, making it a potential biomarker or therapeutic target. Researchers employ MST4 antibodies in techniques like Western blotting, immunofluorescence, and immunoprecipitation to investigate its role in health and disease. Commercial MST4 antibodies are typically validated for specificity against recombinant or endogenous proteins across human, mouse, and rat models, aiding mechanistic studies in cell biology and pathophysiology.