Protein expression of the pro-metastasis genes was further examined in BC cells by western blot and immunofluorescence, and the results suggested that miR-101-3p expression was inversely related with COX-2, ST6GALNAC5 and HBEGF with highest expression of pro-metastasis genes detected in brain metastatic MDA231Br cells (Figure 1D,E). The gene discussed is PTGS2; the disease is breast cancer.