Expression levels of cyclin D1 mRNA in human lung fibroblasts during exponential growth. Quantitative real-time RT-PCR was performed on three separate human lung fibroblast cell lines from IPF patients (HIPF, LL29, and LL97a) and normal control equivalents CCD8LU. Quantification of mRNA was performed by determining the threshold cycle; and standard curves were constructed using the values obtained from serially diluted positively expressing human cDNA. All cells were under conditions of exponential growth (10% FCS supplemented media). 3 PCR reactions were performed from 3 independent cell culture experiments, graph represents mean cyclin D1 expression ± S.E.M; * = p < 0.05.