(2010) Allosteric ligands of the glucagon-like peptide 1 receptor (GLP-1R) differentially modulate endogenous and exogenous peptide responses in a pathway-selective manner: implications for drug screening
The reason is that peptides are naturally occurring substances in the body
Kurz T, Yamada KA, DaTorre SD, Corr PB
Gaikwad S, Puangmalai N, Bittar A, Montalbano M, Garcia S, McAllen S, Bhatt N, Sonawane M, Sengupta U, Kayed R (2021) Tau oligomer induced HMGB1 release contributes to cellular senescence and neuropathology linked to Alzheimers disease and frontotemporal dementia
2.9 Nitric oxide synthase, endometrium, and myometrium Expression of endothelial and inducible NO synthase have been demonstrated in the human endometrium [115], and the endometrial vessels [116]