Compound A5b, also known as JMJD3/HDAC-IN-1, is a dual inhibitor that targets both JMJD3 (Jumonji domain-containing protein demethylase 3) and HADC1 (histone deacetylase, IC50 = 16 nM). It induces hypermethylation of histone H3K27 and hyperacetylation of H3K9, while also promoting apoptosis through the cleavage of caspase-7 and PARP. This compound has demonstrated the ability to effectively inhibit cancer cell cloning, migration, and invasion [1].