PTGS2 and breast ductal adenocarcinoma: In one study, intermediate or high levels of COX-2 were detected in 43% of Human Breast cancer carcinomas and in 62.5% of Ductal Carcinoma in Situ, and also COX-2 expression was found in MCF-7 breast cancer cell line induced by HER2 and no COX-2 proteins in MCF-7 cells alone [9].