MicroRNAs, a class of non-coding RNAs that are important for regulating gene expression. Inside of graph shows yellow and blue colors thoughout. Left side reads "743 microRNAs" and "10,170 tumors." This is a heatmap showing the intensity of the color correlating to the presence of different microRNA groups.

Today, scientists can examine data “heat maps,” which show genetic activity profiles from thousands of tumors at one time. This one shows MicroRNAs, a class of non-coding RNAs that are important for regulating gene expression.