Spermidine in hormone-dependent differentiation of mammary gland in vitro.

Stiulation of milk-protein synthesis in mouse mammary epithelium in vitro requires insulin, hydrocortisone, and prolactin. The requirement for hydrocortisone can be replaced by spermidine. The possibility that spermidine mediates the effect of glucocorticoid is also supported by the observation that the cellular spermidine concentration increases before the accelerated synthesis of casein and alpha-lactalbumin.