Lactoferrin is a marker for prolactin response in mouse mammary explants.

We recorded a bioassay for prolactin using densitometric analysis on polyacrylamide gels of caseins produced by mammary explants in vitro. A protein which also increased in the presence of increasing amounts of prolactin in the medium has now been identified. Its migration in several electrophoretic systems is the same as that of a whey protein of mouse milk, lactoferrin. It is an iron-binding glycoprotein with a molecular weight by SDS gel electrophoresis equal to mouse, human and bovine lactoferrin. It gives a precipitin reaction in an immunodiffusion system with monospecific antiserum raised in rabbits against mouse lactoferrin.