A large number of microRNAs (miRNAs) are detected in serum. Box-and-whisker plots showing the log (2)-normalized expression for the 47 miRNAs which are expressed above background in 400 individuals. Expression levels were adjusted for batch and chip lot across all samples. The black line represents the median, and the upper and lower 25% are the top and bottom of the box, respectively. Dots represent the outliers.