In various cancer cell lines in vitro, inhibition of the enzymatic activity of PDE1 or PDE4 isoenzymes, increases cAMP level, leading to growth arrest or apoptosis [33],[34],[35] while the selective PDE3 inhibitor cilostazol has been reported, in a single report, to reduce colon cancer cell motility [36]. This evidence concerns the gene PDE4A and malignant colon neoplasm.