AUTHOR=Tiwari Amit K., Chen Zhe-Sheng TITLE=Repurposing phosphodiesterase-5 inhibitors as chemoadjuvants JOURNAL=Frontiers in Pharmacology VOLUME=4 YEAR=2013 URL=https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2013.00082 DOI=10.3389/fphar.2013.00082 ISSN=1663-9812