Drugs that upregulate {TAIL ~ the concentration} of cAMP in {HEAD ~ cells} are well known 
Drugs that upregulate { TAIL ~ the concentration } of cAMP in { HEAD ~ cells } are well known
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH