Fig. 5.

STAT5a nuclear import is required for the transcription of the β-casein promoter and synergy with GR. (A) T47D human breast cells were transfected with luciferase reporter regulated by β-casein gene promoter, β-galactosidase (β-gal) control and STAT5a wild-type or import mutation. After serum starvation, cells were left untreated (CTRL) or treated with prolactin (PRL) or/and hydrocortisone (HC) for 16 hours to activate STAT5a or GR. The level of β-casein gene expression was measured by luciferase assay and normalized to β-gal activity. (B) MCF-7 human breast cells were co-transfected with human prolactin receptor, GR-V5, HA-STAT5a wild type or import mutation and treated with PRL or HC. Immunofluorescence of HA-STAT5a and GR-V5 was detected using either FITC- or Texas Red-conjugated secondary antibody, respectively. Fluorescence intensity measurements are provided in supplementary material Fig. S4. Images represent the majority of transfected cells.