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