{HEAD ~ Signal suppression} of lower abundance proteins by high abundance proteins presents {TAIL ~ a significant challenge} to SELDI mass spectrometry 
{ HEAD ~ Signal suppression } of lower abundance proteins by high abundance proteins presents { TAIL ~ a significant challenge } to SELDI mass spectrometry
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH