Cell line PER-278 was established from a bone marrow sample of a 10-year-old boy diagnosed with pre-B acute lymphoblastic leukemia (ALL). PER-278 cells show the pre-B phenotype, express cytoplasmic Ig, and exhibit two translocations: t(1;19)(q23;p13) and t(1;9)(q23;p13). Assessment of the immunoglobulin rearrangements confirmed the clonal origin of cell line PER-278, and comparison with the patients's leukemic cells showed an identical pattern: loci involved at the breakpoint on chromosome 1 code for the oncogene SKI and for the Fc receptor II and on chromosome 19 for the insulin receptor. The t(1;19) may contribute to the malignant transformation in leukemic cells of pre-B phenotype.