Engineering and production of recombinant bovine pancreatic ribonuclease enzyme (RNase A) as a potential therapeutic Masoume Vakili-Azghandi PhD Student, Animal Science Department, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran. Tel. +989354657772. Email: m.vakili2009@gmail.com Mohammadreza Nassiri *Corresponding author: Professor, Recombinant proteins research group, The research institute of biotechnology, Ferdowsi University of Mashhad, Mashhad, Iran. Tel. +98 51 38795618. Email: nassiryr@um.ac.ir Shahrokh Ghovvati Assistant Professor, Animal Science Department, Faculty of Agriculture, University of Guilan, Rasht, Iran. Tel. +989113313260. Email: Ghovvati@guilan.ac.ir Ali Javadmanesh Assistant Professor, Animal Science Department, Faculty of Agriculture and Stem Cell Biology and Regenerative Medicine Research Group, Research Institute of Biotechnology, Ferdowsi University of Mashhad, Mashhad, Iran. Tel. +989113716048. Email: javadmanesh@um.ac.ir Abstract Objective Immunotoxins are one of the most promising ways in therapeutic fields, specially cancer therapy which have a unique toxin-antibody structure, and kill the cancer cell by passing through the cell membrane and entering the target cell. The aim of this study was to engineer and design bovine pancreatic enzyme (RNase A) for to escape from ribonuclease inhibitor (RI) as a toxin segment in designing of immunotoxins used in therapeutic fields.