PIR and breast carcinoma: For instance, many of the downregulated piRNAs (piR-31636, piR-57125, piR-35548 and piR-57125) were previously found upregulated in breast cancer growing cells and/or in breast tumors compared to their normal tissues, whereas many of the upregulated piRNAs were previously associated to a breast cancer growth arrested phenotype (piR-36743, piR-36318, piR-36249, piR-43772, piR-36041) [10].