Two regions of homozygous deletion clusters at chromosome band 9p21 in XXXX @entity2 .

@entity1 @entity2 @entity5 @entity986
We examined 149 @entity2 cell lines for homozygous deletions using 24 DNA markers, which were mapped and ordered in chromosome band 9p21, to define the target regions for 9p21 deletions in @entity1 @entity2 . Homozygous deletions were detected in 39 (26%) cell lines and clustered at 2 independent regions. One was the region containing the @entity986 / @entity986 @entity5 suppressor gene, and this region was deleted in 32 (21%) cell lines. The other was the region containing D9S171, which is the locus approximately 3 Mb proximal to the @entity986 locus. This region, designated as the D9S171 region, was deleted in 18 (12%) cell lines. Seven of the 18 cell lines had identical minimum deletions of a 17,036 bp sequence located 20 kb distal to the D9S171 locus. However, such a deletion was also observed in the corresponding B-lymphoblastoid cell line from 1 of the 7 cell lines and in 5 (16%) of 32 noncancerous tissues, suggesting that the deletion was a genetic polymorphism. By considering this polymorphism, 11 (7%) cell lines still had deletions at the D9S171 region. Two NSCLC cell lines showed deletions at the D9S171 region and retentions of the @entity986 locus. Furthermore, an NSCLC cell line showed discontinuous deletions including either the @entity986 or D9S171 locus. Therefore, the region surrounding the D9S171 locus was defined as another target region for the 9p21 deletions. It is possible that unknown @entity5 suppressor gene(s) are present in this chromosomal region. Genes Chromosomes Cancer 27:308-318, 2000.
