In other embodiments the cell or its ancestors was genetically altered with a vector to place {HEAD ~ X} under {TAIL ~ control} of an endogenous transcriptional control element 
under
In other embodiments the cell or its ancestors was genetically altered with a vector to place { HEAD ~ X } under { TAIL ~ control } of an endogenous transcriptional control element
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH