Fig 2. Technical replicability of microRNA quantification by microarray and reverse transcription (RT)-PCR.
(A) The two scatter-plots show the inter-duplicate correlation of microRNA quantifications for two RNA samples (RNA 1 and 2) that were analyzed with microarrays in duplicate. Microarray signal values for the 598 expressed human microRNAs of this study are plotted for the two pairs of duplicates. Also shown are the coefficients of Pearson correlation (r, rounded to two decimal places), and their 95% confidence intervals and associated two-tailed P values, and the slopes (m) of the linear regression lines (ordinary least squares method) and their 95% confidence intervals. To depict the relatively poor correlation for microRNAs with low signals, a rolling window of width 99 along the X axis was used for calculating r at the mid-window abscissa and plots of these r values are shown in grey. (B). MicroRNAs let-7a-5p, let-7g-5p, miR-93-3p, miR-126-3p, and miR-942-5p, and the RNU6-2 (U6B) small RNA were measured in a reference RNA in ten separate batches of RT-PCR assays. Raw (left) and RNU6-2-normalized (right) quantification cycle (Cq) values from the ten assays, and their means and standard deviations are plotted.