Used in biomedical research to quantitatively measure Smad4 protein levels in human biological samples such as serum, plasma, and cell lysates. The kit supports studies on TGF-β signaling pathways, which play key roles in cell growth, differentiation, apoptosis, and immune regulation. It is widely applied in cancer research, particularly in understanding tumor progression and metastasis in colorectal, pancreatic, and other cancers where Smad4 expression is altered. The assay enables high-throughput screening and validation of therapeutic targets in drug development and helps assess disease mechanisms in inflammatory and fibrotic disorders.