Experimental: The monophosphopeptide sample was dissolved in water containing 0.1% trifluoroacetic acid at a concentration of 10 pmol/μL. The matrix for this analysis was made by mixing 150 μL of CHCA (Methanol) at a concentration 30 mg/mL with 35 mg of 3-Aminoquinoline. Next, the monophosphopeptide sample solution and matrix solution were mixed together 1:1 by volume. Afterwards, 0.5 μL of this mixture was placed on the MALDI target plate (2.5 pmol/spot). Finally, the sample spot was measured using the TOFTOF option available on the JMS-S3000 SpiralTOF MS system.