A molecular rearrangement of the proto-oncogene c-myc located downstream of the exon III 3' end has been found in a cell line derived from KE37 cell line established from an acute T-lymphoblastic leukemia. This rearrangement resulted from a chromosomal translocation t(8; 14)(q24; q11). Since the 14q11 chromosomal band has been found to be involved in several T-cell leukemias and lymphomas, the importance of the rearrangement of c-myc discovered in the KE37 cell line lies in the possibility of analyzing chromosome 14 DNA near the breakpoint involved in the translocation.