Simvastatin abrogates cyclin D1 gene expression levels in a dose dependent fashion in human lung fibroblasts. Serum deprived cells were incubated with Simvastatin (Sim 0.1–10 μM) for 16 hours. Subsequent TGF-β1 stimulation (5 ng/ml) was carried out for 8 hours. Experiments were performed in three separate human lung fibroblast cell lines from IPF patients (HIPF, LL29, and LL97a) and normal control equivalents CCD8LU. The control shown represents fibroblasts not exposed to Simvastatin and/or TGF-β1. The gene expression of cyclin D1 was then determined by real time PCR. Data shown demonstrates analysis from LL97a and CCD8LU fibroblasts. Data is representative of the mean of triplicate PCRs obtained from 3 independent experiments. Data are expressed as the mean fold change in cyclin D1 expression ± SEM. * = p < 0.05 compared to control untreated, † = p < 0.05 compared to TGF-β1 treatment.