RNA-binding proteins are key player in processes occurring inside cell. In this study, we use Optical Tweezers to characterize the mechanisms involved in the interaction of the protein Thymidilate Synthase and its messenger RNA, as they play a key role in determining the efficiency of chemotherapies against solid cancers. This study is carried out in collaboration with prof. M.P. Costi (univ. Modena and Reggio Emilia) in the frame of an AIRC project.