PTGS2 and cancer: It has also been proposed that the overexpression of genes, like cyclooxygenase-2 (COX-2), in cancer cells (Gupta and Dubois, 2001; Romano and Claria, 2003; Tuynman et al, 2004) may be due to the disruption of a control network in which relevant microRNA genes are implicated (Michael et al, 2003; Bartel, 2004; He et al, 2005; Lu et al, 2005).