GSK J4 HCl is primarily utilized in research settings to study its role as an inhibitor of histone demethylases, specifically targeting the KDM6 subfamily, which includes enzymes like UTX and JMJD3. Its application is significant in understanding epigenetic regulation, particularly in the context of gene expression and cellular differentiation. Researchers employ this compound to investigate its effects on various biological processes, such as immune response modulation, cancer progression, and stem cell maintenance. By inhibiting these demethylases, GSK J4 HCl helps elucidate the mechanisms underlying chromatin remodeling and its impact on disease states, making it a valuable tool in epigenetic and therapeutic research.