AZ191 is a selective inhibitor of the anaplastic lymphoma kinase (ALK) pathway, primarily used in research settings to study ALK-dependent signaling in cancer cells. It is applied in preclinical studies to investigate tumor growth suppression, particularly in non-small cell lung cancer and other malignancies driven by ALK fusion proteins. Due to its high specificity, AZ191 helps researchers evaluate the downstream effects of ALK inhibition, such as reduced cell proliferation and induction of apoptosis. It is also used to assess mechanisms of resistance to ALK-targeted therapies and to explore combination treatment strategies with other kinase inhibitors. Its application remains confined to laboratory research and is not approved for clinical use.