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