PIWIL1 and cancer: Ranking 7385 piRNAs containing expression counts in at least one patient in order of positive to negative correlation with PIWI protein expression, we evaluated all piRNAs in our set of 30 HPV-dysregulated piRNAs for significant enrichment, separating upregulated (n = 24) and downregulated (n = 6) transcripts in order to match enrichment results to direction of dysregulation in cancer.