The present invention provides novel PAR1 derived cytoprotective oligopeptides or polypeptides which typically contain at least the first 4 N-terminal residues that are substantially identical to the corresponding N-terminal residues of Met1-Arg46 deleted human PAR1 sequence. These cytoprotective oligopeptides or polypeptides are capable of activating PAR1 and promoting PAR1 cytoprotective signaling activities. The invention also provides engineered cells or transgenic non-human animals which harbor in their genome an altered PAR1 gene that is resistant to cleavage at Arg41 and/or Arg46 residues. Additionally provided in the invention are methods of screening candidate compounds to identity additional cytoprotective compounds or cytoprotective proteases. The invention further provides therapeutic use or methods of employing a PAR1 derived cytoprotective oligopeptide or polypeptide to treat conditions associated with tissue injuries or undesired apoptosis.
