Linked from
The 12 pages that link to Peptide hormone, each with the reason it gives.
ProlactinNarrower topic: Prolactin is a protein hormone that acts through cell-surface receptors.
HormoneBroader topic: Insulin and many pituitary signals belong to this widely used hormone class.
OxytocinRelated: Oxytocin’s peptide structure prevents it from freely crossing cell membranes.
PeptideBroader topic: Insulin and glucagon show how peptides can act as systemic signals.
EndorphinsRelated: Some endorphins also function as hormones when released into the bloodstream.