Illumina single-end microRNA sequence (miRNA-seq) data were profiled and normalized as described previously [1] with following modifications.  All analyzed libraries met the requirement of 1 million miRNA-aligned reads, and the expression matrix was generated based on the miRBase v19 annotation. 

Reference
[1] Cancer Genome Atlas Network. Comprehensive molecular portraits of human breast tumours. Nature. 2012;490(7418):61-70. PMID:23000897