Used to measure activin A levels in biological samples such as serum, plasma, and cell culture supernatants. Widely applied in research settings to study reproductive biology, inflammation, and tissue regeneration. Helps investigate roles of activin A in ovarian function, pituitary hormone regulation, and immune responses. Also used in studies related to fibrosis, cancer progression, and metabolic disorders. Provides a sensitive and specific quantification method for monitoring changes in activin A under experimental or pathological conditions.