Thanks to the growing studies of KDM6B, GSK-J4 has been applied to different kinds of tumors such as T-ALL, diffuse large B-cell lymphoma, pediatric brainstem glioma and prostate cancer with dismal toxicity for normal hematopoietic progenitor cells (Hashizume et al. 2014; Mathur et al. 2017; Morozov et al. 2017; Ntziachristos et al. 2014). The gene discussed is KDM6B; the disease is acute lymphoblastic leukemia.