{TAIL ~ Expression} of the effector gene results in expression of {HEAD ~ a cell surface antigen} that can be used to deplete the undifferentiated cells 
{ TAIL ~ Expression } of the effector gene results in expression of { HEAD ~ a cell surface antigen } that can be used to deplete the undifferentiated cells
TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH