For example, a 21-gene assay was found helpful to assist in adjuvant treatment decision in hormone receptor-positive breast cancer patients.[18] An 8-gene expression signature could help to predict the survival and time to the treatment of chronic lymphocytic leukemia,[19] and a 6-gene signature was found to be able to distinguish 4 subgroups of neuroblastoma.[20] In drug abuse, no such study was reported yet in the literature to our knowledge. The gene discussed is NR4A1; the disease is B-cell chronic lymphocytic leukemia.