Several studies have shown that JMJD3 depletion by GSK-J4 chemical inhibitor, an ethyl ester derivative of GSK-J1, could offer a new therapeutic approach in various diseases [28–30], and highlight its anti-tumor activities on brainstem gliomas and breast cancer stem cells in xenograft models [31, 32]. The gene discussed is KDM6B; the disease is breast cancer.