Mature miRNA expression in human cell lines and hepatocytes. Total RNA, including the small RNAs, was isolated from three different human hepatocytes preparations and from the HeLa and HepG2 cell lines. To show the variability between hepatocyte preparations, the results from each hepatocyte preparation are graphed separately. RT-PCR assays were performed with U6 snRNA as the internal control. The relative miRNA expression was calculated as 2−(ΔCt). Values were multiplied by 103 to simplify data presentation. The values shown in the graph were obtained from triplicate assays in a single PCR experiment. Error bars are not shown because true biological replicates (plated on different days) cannot be obtained from human hepatocyte isolations. Therefore, separate bars are shown for each hepatocyte preparation. A, expression of hsa-miR-34a. B, expression of hsa-miR-34b*, hsa-miR-34c-5p, and hsa-miR-449a.