Molecular and enzymatic characterization of XMRV protease by a cell-free proteolytic analysis

► A cell-free proteolytic analysis for retrovirus protease (PRs) was developed. ► Amprenavir was identified as a potent XMRV PR inhibitor. ► The physical interaction between APV and XMRV PR was delineated. ► Several tumor suppressor proteins were revealed to be substrates of XMRV PR.