PTGS2 and breast carcinoma: Combined gene and microRNA expression microarrays with ectopic COX-2 overexpressing and Mock (empty vector-transfected) MCF7 breast cancer cells [6] revealed 26 genes that are downregulated, along with two microRNAs, miR-526b [11] and miR-655 [12] that are upregulated by COX-2.