PK and menaquinone (MK) 4 plasma and tissue concentrations were measured by HPLC. 
HPLC
Long-chain MKs were measured in all matrices by LC-atmospheric pressure chemical ionization-mass spectrometry. 
LC-atmospheric pressure chemical ionization-mass spectrometry
Gene expression was quantified by reverse transcriptase-polymerase chain reaction in the liver, brain, kidney, pancreas, and adipose tissue.



reverse transcriptase-polymerase chain reaction