In our study, we found an increase in adipocytes in the BMM after exposure to chemotherapeutic drugs by utilizing matched BM biopsies taken from five adult T‐ALL patients at initial diagnosis and after induction therapy and then confirmed that the BMSC‐derived adipocytes attracted T‐ALL cells by CXCL13 and supported T‐ALL cells via the DLL1/Notch1 signaling pathway. This evidence concerns the gene DLL1 and acute lymphoblastic leukemia.