Anti-CST4 Antibody

Cystatin S (cystatin 4) is a small secreted cysteine protease inhibitor of the type 2 cystatin superfamily, abundant in human saliva, tear fluid, and other exocrine secretions and best known for controlling lysosomal cathepsin activity in mucosal and glandular environments. The Antibodies.com rabbit polyclonal anti-CST4 reagent is supplied as 100 µl of unconjugated IgG in a single vial, affinity-purified and validated for Western blot and immunohistochemistry on human, mouse, and rat samples. Because the polyclonal format recognises multiple epitopes across the target, the same lot supports chromogenic IHC on formalin-fixed paraffin-embedded sections, indirect immunofluorescence on cultured cells, and standard SDS-PAGE immunoblotting of cell or tissue lysates.

CST4 has drawn sustained interest in saliva-based proteomics and has been explored as a candidate biomarker in colorectal cancer screening studies, where sensitive detection of endogenous cystatin S in epithelial tissue is required. The unconjugated format leaves the user free to pair the primary with a preferred HRP-, biotin-, or fluorophore-conjugated secondary antibody, accommodating both enzyme-amplified and fluorescence readouts without the constraints of a pre-labelled reagent. Short-term storage at 4 °C is acceptable for active use, while long-term retention at -20 °C is recommended for stock vials; aliquoting the 100 µl volume helps limit loss of titre across repeated freeze-thaw cycles and preserves batch-to-batch consistency. Each preparation is backed by lot documentation and intended for research use only, supporting reproducible detection in published experimental settings.