Hebrews 5:12 (Go to this verse :: Verse pop-up). In context, God tells us one of the purposes of His revelation to mankind. The writer of Hebrews scolds his audience for being dull of hearing (verse 11).
Prostaglandin activity is also intense but short lived, though the symptoms of the resulting inflammation continue for some time after prostaglandin release stops. Mast cells are the main source of prostaglandin synthesis and secretion. Epithelial cells (surface cells of the SKIN and mucous membranes) and platelets also produce as well as respond to prostaglandins.
Proinsulin is the prohormone precursor to insulin made in the beta cells of the islets of Langerhans, specialized regions of the pancreas. In humans, proinsulin is encoded by the INS gene. The islets of Langerhans only secrete between 1% and 3% of proinsulin intact.