the differentiation promoter sodium butyrate increases the content of met5-enkephalin-arg6-gly7-leu8 ( met5-enk-rgl ) -immunoreactive peptides in pc12 pheochromocytoma cells , which , unlike mature adrenomedullary chromaffin cells , contain exceedingly low levels of opioid peptides .
C0014298
enkephalin
C0205753
opioid peptides