Tubastatin A HCl is primarily used as a selective inhibitor of histone deacetylase 6 (HDAC6), making it a valuable tool in epigenetic research. It is widely applied in studies related to cancer biology, where HDAC6 inhibition has been shown to induce apoptosis and suppress tumor growth. Due to its ability to modulate protein acetylation, particularly of α-tubulin, it is also used in neuroscience research to investigate neurodegenerative diseases such as Alzheimer’s and Parkinson’s, where impaired protein degradation and transport are involved. Additionally, Tubastatin A HCl has been explored in inflammation and immune response studies, as HDAC6 plays a role in regulating inflammatory pathways. Its selectivity for HDAC6 over other HDAC isoforms makes it useful for probing specific cellular mechanisms without broad off-target effects.