Characterization of the submicroscopic deletion in the small-cell lung carcinoma (SCLC) cell line U2020

The small‐cell lung carcinoma cell line U2020 contains a submicroscopic, homozygous deletion that removes a chromosomal segment within 3p13‐p14, including the locus D3S3. We have sublocalized 49 additional probes to the 3p13‐p14.2 region and have identified 7 new DNA markers that arise from within the U2020 deletion. The estimated size of the deletion, based on marker density, is approximately 4–5 megabases (Mb). Including D3S3, 7 of the 8 markers have been linked by pulsed‐field gel (PFG) electrophoresis over an area of approximately 2 Mb. Including the one unlinked marker, PFG analysis accounts for about 3 Mb of the region. The U2020 deletion appears confined to the 3p13‐p14.2 region and does not include the candidate tumor suppressor gene, protein‐tyrosine phosphatase gamma (PTPG).