day <span  title="" class="an ">&ensp;</span>old <span  title="" class="an ">&ensp;</span>rats <span  title="" class="an ">&ensp;</span>P <span  title="" class="an ">&ensp;</span>P <span  title="" class="an ">&ensp;</span>by <span  title="" class="an ">&ensp;</span>using <span  title="" class="an ">&ensp;</span>minimal <span  title="" class="an ">&ensp;</span>protease <span  title="" class="an ">&ensp;</span>exposure <span  title="" class="an ">&ensp;</span>followed <span  title="" class="an ">&ensp;</span>