PRL transcript in BMSC identified by RT-PCR. Passaged stromal layers were cultured in the absence (lane 1) or presence of PAF for 5 (lane 2) and 20 (lane 3) hours, or PAF plus the PAF-R antagonist WEB 2170 (20 hours) (lane 4). Total cell RNA was reverse transcribed and cDNA was amplified using PRL-specific primers and various amplification cycles as described in Materials and Methods. Lane 7 is the no-template control. The base-pair length was determinated with marker DNA fragments (left). Positive and negative controls for PRL mRNA were IM9-P3 (lane 5) and Hep-G2 (lane 6). β-Actin gene expression was also examined as an internal control to ensure RNA integrity and proper amplification. Data are representative of three experiments.