Hierarchical clustering of significantly changed miRNAs in NPC versus normal control tissue. Hierarchy heatmap generated using a Euclidean distance metrics and centroid linkage method. Expression levels of each miRNA in each samples are represented by different colors signifying hybridization intensities. Superscript numbering on sample names denotes those from the same individual (paired NPC/control tissue). Further analysis with statistical information is presented in Additional file 3.