an>effect <span  title="" class="an ">&ensp;</span>was <span  title="" class="an ">&ensp;</span>specific <span  title="" class="an ">&ensp;</span>for <span  title="" class="an ">&ensp;</span>P <span  title="" class="an ">&ensp;</span>Y <span  title="" class="an ">&ensp;</span>P <span  title="" class="an ">&ensp;</span>Y <span  title="" class="an ">&ensp;</span>receptors <span  title="" class="an ">&ensp;</span>as <span  title="" class="an ">&ensp;</span>the <span  title="" class="an ">&ensp;</span>P <span  