PTGS2 and ovarian cancer: The importance of the down-regulation of metastasis-associated in colon cancer 1 (MAAC1), metastasis-associated 1 (MTA1), and cyclooxygenase 2 (COC2) genes in ovarian cancer induction and progression was demonstrated by several studies, employing the down-regulation of their expression by shRNA/siRNA strategies [67,68,69,70].