PDE3A and gastrointestinal stromal tumor: In contrast, we observed in GIST cell lines, that cilostazol effect on YAP inactivation/nuclear exclusion and reduction of cell viability was not accompanied by modification of cAMP levels, suggesting other, cAMP-independent, mechanism(s), such as allosteric inhibition already reported for PDE4 [41, 42] and for PDE3A by De Waal in HeLa cells [16].