Some of the effects of certain known drugs may be dependent upon {HEAD ~ their ability} to upregulate {TAIL ~ IRS2} 
to upregulate
Some of the effects of certain known drugs may be dependent upon { HEAD ~ their ability } to upregulate { TAIL ~ IRS2 }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL