Figure 4.

The up-regulation of Brca1 and Brca2 by glucocorticoids requires a serum factor(s). (A) mRNA expression of Brca1, Brca2, histone H2B, β-casein, and actin in HC11 mammary epithelial cells that were either actively growing (Active) or postconfluent at the times indicated after induction with lactogenic hormones (insulin, hydrocortisone, and prolactin) in the presence of charcoal-stripped serum. The 28S RNA band is shown from an ethidium bromide-stained nitrocellulose blot as a loading control. (B) Hormonal requirements for Brca1 and Brca2 up-regulation in HC11 cells in charcoal-stripped or whole serum. mRNA expression of Brca1, Brca2, and histone H2B in postconfluent HC11 cells that were treated in the presence of charcoal-stripped or whole serum with the hormones indicated for 7 days in differentiation medium. Dex, dexamethasone; Ins, insulin; Prl, prolactin.