PTGER4 and breast cancer: Elevated COX-2 expression associated with a large tumor size, a high histological grade, a negative hormone receptor status, a high proliferation rate, high p53 expression, and the presence of HER-2 oncogene amplification along with axillary node metastases and a ductal type of histology [98]. COX-2 inhibition may potentially prevent the development of ER-positive and ER-negative breast cancers [98]. Expression of PGE2 and IL-8 [101]. COX-2 over-expression induces an oncogenic microRNA (miR655) in human breast cancer cells by activation of EP4 [102].