Protein biomarkers are specific proteins in the body that can serve as indicators or markers of a biological process, disease, or condition. They are often measured in biological samples such as blood, urine, or tissue, and can provide important information about the health status of an individual. Protein biomarkers are used in various fields of research, such as cancer diagnostics, drug development, personalized medicine, and monitoring of disease progression. They play a crucial role in the identification, diagnosis, and monitoring of diseases, as well as in predicting response to treatments and assessing treatment outcomes.