For the sake of achieving a deeper insight into the CSC properties in CD9-expressing cells of B-ALL cell lines, the authors performed detailed assays and showed that CD9 regulates the cancer-related genes, such as TEL/AML1 and E2A/PBX1, in B-ALL and significantly affects Src family proteins involved in diverse biological functions. This evidence concerns the gene PBX1 and acute lymphoblastic leukemia.