{HEAD ~ The recombinant transfection system} 22, wherein {TAIL ~ the transcriptional regulatory sequence} is a conditional transcriptional regulatory sequence 
wherein
{ HEAD ~ The recombinant transfection system } 22 , wherein { TAIL ~ the transcriptional regulatory sequence } is a conditional transcriptional regulatory sequence
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH