Genomic deletions cause truncation of cyclin D1a mRNA. Proximal and distal 3′UTR probes were used to amplify genomic DNA, and the ratio of the respective amplification strength was determined. The black square indicates the mean in tumors with normal cyclin D1a mRNA transcripts (n = 69), and the bars represent the standard deviation of this mean estimate. Individual tumor samples expressing truncated cyclin D1a mRNA transcripts are represented by triangles (n = 14, for one patient no DNA was available). Samples with a ratio of distal/proximal UTR below the 5th percentile of the samples with normal cyclin D1 locus (n = 69, black squares) were considered to have a genomic deletion of the 3′UTR.