Figure 2.

Ribonuclease protection assay of PBP transcript levels. Total RNA (10 μg) was hybridized with radiolabeled antisense PBP probe generated by in vitro transcription. Glyceraldehyde-3-phosphate dehydrogenase probe was included in each hybridization reaction as control. Nuclease resistant fragments were resolved on 6% polyacrylamide-urea gels. High levels of expression of PBP mRNA are seen in breast tumor samples A1, A8, B3, and B6 and in MDA-MD-361 breast cancer cell line (A4). Samples B7 and B8 are breast tumors with no appreciable increase in PBP transcript, and sample C1 is normal human mammary gland RNA.