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The murine lck gene is closely related to a family of cellular protooncogenes and encodes a lymphocyte-specific, membrane-associated protein tyrosine kinase. We and others have demonstrated that the lck gene is rearranged and overexpressed in the murine lymphoma LSTRA, most likely as a result of the insertion of Moloney murine leukemia virus DNA immediately adjacent to the gene. We now report that the lck gene is located at the distal end of murine chromosome 4 and on human chromosome 1 at position 1p32-35 near a site of frequent structural abnormalities in human lymphomas and neuroblastomas. These results raise the possibility that structural alteration of the lck gene through chromosomal rearrangement may contribute to transformation in human malignant disease.

A reciprocal translocation involving chromosomes Nos. 3 and 22 has been found in a patient with seemingly Ph-negative chronic myelogenous leukemia (CML). G-band analysis revealed, that deletion in No. 22 occurred at the same point, as in the typical cases of the disease. It was concluded, that breakage in No. 22 at a specific site with spatial disjunction of the resulting segments might be the crucial cytogenetic event in the genesis of CML, the Philadelphia chromosome not being an obligatory result of the rearrangement.