Abbreviations
MS mass spectrometry
LC liquid chromatography
PTM post-translational modification
MRM multiple reaction monitoring
PDE phosphodiesterase
cGMP cyclic guanosine monophosphate
FDR false discovery rates
2D two-dimensional
SAF spectral-abundance-factor

Authors’ contributions
All authors contributed to the writing and conceptualization of the manuscript. All authors read and approved the final manuscript.

Acknowledgements
None.

Competing interests
The authors declare no financial and non-financial competing interests.

Funding
This work was supported by National Institutes of Health Grants: NIH U54GM114833, NIH R01HL129723 to Dr. Peipei Ping and NIH K99HL127302 to Dr. Maggie Lam.