Cyclin D1a transcripts with full-length and truncated 3′UTRs are expressed in Z-138, but the transcript with a truncated 3′UTR is more stable. (A) Schematic representation of the 2 cyclin D1a transcripts found in Z-138. Lines represent the mRNA, with shaded boxes indicating the coding sequence. Ovals indicate the position of the polyadenylation signal (AATAAA), while the light gray square and the black box represent mRNA destabilizing elements, including an AU-rich element (ARE). PCR probes are represented by filled boxes. (B) Expression of cyclin D1 transcripts in Z-138 cells in relation to beta-2 microglobulin (B2M). (C-E) Relative expression levels of cyclin D1 and B2M transcripts in Z-138 cells after inhibition of transcription with 10 μg/mL actinomycin D.