PTGS2 and breast cancer: Western blotting revealed that following COX-2-shRNA transfection, the expression of the VEGF-A and VEGF-C proteins in the breast cancer MCF-7 cells of the COX-2-shRNA group was significantly lower than that of the blank and mock groups (P<0.05), however, no significant differences were identified between the blank and mock groups (P>0.05) (Fig. 6).