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  <xs:element id="plrx_ReclassificationOfRestrictedStockAwardsFromLiabilitiesToCommonStockUponVesting" abstract="false" name="ReclassificationOfRestrictedStockAwardsFromLiabilitiesToCommonStockUponVesting" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="plrx_AccruedExpensesAndOtherLiabilitiesMember" abstract="true" name="AccruedExpensesAndOtherLiabilitiesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="nonnum:domainItemType"/>
  <xs:element id="plrx_ShareBasedCompensationRestrictedStockAwardsWeightedAverageGrantDateFairValueNotPurchased" abstract="false" name="ShareBasedCompensationRestrictedStockAwardsWeightedAverageGrantDateFairValueNotPurchased" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="num:perShareItemType"/>
  <xs:element id="plrx_NumberOfIntegrinResearchTargets" abstract="false" name="NumberOfIntegrinResearchTargets" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="plrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentOfEstimatedFairValueOfShares" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentOfEstimatedFairValueOfShares" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="num:percentItemType"/>
  <xs:element id="plrx_CommonStockFairMarketValuePercentage" abstract="false" name="CommonStockFairMarketValuePercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="num:percentItemType"/>
</xs:schema>
