Used in biomedical research to detect and quantify cytokeratin 19 fragments in biological samples such as serum, plasma, or cell culture supernatants. Widely applied in cancer studies, particularly for monitoring tumor progression and recurrence in carcinomas including lung, breast, and liver cancers. Helps assess epithelial cell damage or turnover in clinical and research settings. Commonly used in diagnostic laboratories for evaluating disease markers and in drug development to measure treatment response. Suitable for research use only, not for diagnostic procedures in humans.