Retraction notice to "Design, synthesis, and biological evaluation of heterotetracyclic quinolinone derivatives as anticancer agents targeting topoisomerases" [Eur. J. Med. Chem. 190 (2020) 112074].

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the authors. The authors regret to inform that they would like to withdraw this accepted article, due to serious errors in authorship, affiliations, material sources and supporting grant names/numbers. The authors sincerely apologize for these oversights and miscommunications the study caused.