Effect of increasing concentration of AMP on the phosphorylation of 13-mer synthetic peptides centralized around S151 of Arhgef2, S151 of Crtc1 and S559 of Lipe in presence of various SNF1-subfamily protein kinases. Human recombinant (A) MARK3, (B) SIK2, (C) NUAK2, (D) MELK were used for the in vitro phosphorylation reaction. PRM-MS assay was used to measure the chromatogram area of phosphorylated peptide precursors. X-axis indicates the ratio of chromatogram area of phosphorylated peptides (based on precursor mass) following incubation with various concentrations of AMP (10, 100 μM) when compared to ‘no AMP’ (0 μM). An x-axis value of 1.0 indicates no change. AMARA and SAMS were included as control peptides.