AG 555 is primarily used in biochemical research as a selective inhibitor of the epidermal growth factor receptor (EGFR) tyrosine kinase. It is employed to study the role of EGFR signaling pathways in various cellular processes, including cell proliferation, differentiation, and survival. Researchers utilize AG 555 to investigate its potential effects in cancer biology, as EGFR is often overexpressed or mutated in many types of cancers. By inhibiting EGFR activity, AG 555 helps in understanding the mechanisms of tumor growth and in exploring therapeutic strategies for cancer treatment. Additionally, it is used in experimental models to assess the impact of EGFR inhibition on other diseases where EGFR signaling may play a critical role.