Then she started to induction chemotherapy with imatinib (400 mg/d), cyclophosphamide, daunorubicin, vincristine and prednisolone referring to the Treatment Guideline for China Adult Acute Lymphocyte Leukemia, and achieved complete response by morphology and immunophenotype, the BCR-ABL gene quantification decreased to 1%, and the chromosomal karyotype returned to normal, but a new gene mutation E255V was detected in the ABL kinase region which was moderately sensitive to dasatinib and resistant to imatinib. This evidence concerns the gene ABL1 and acute lymphoblastic leukemia.