Hormone-Dependent Differentiation of Mammary Gland: Sequence of Action of Hormones in Relation to Cell Cycle

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Science  19 May 1967:
Vol. 156, Issue 3777, pp. 945-946
DOI: 10.1126/science.156.3777.945


Differentiation of mouse mammary gland in vitro requires insulin, hydrocortisone, and prolactin. The epithelial cells must first divide in order to synthesize casein in response to these hormones. Insulin is required for the initiation of DNA synthesis and is also necessary during G1 phase (after mitosis). Prolactin can elicit the overt differentiative responses after mitosis. Activity of hydrocortisone precedes that of prolactin, that is, after mitosis it is not capable of eliciting the differentiative response.