A transient STAT5 activation is not sufficient to induce mammary-specific gene expression. (A) Confocal images of Cy5.5-labeled Prl incubated EpH4 cells. EpH4 cells were cultured in 2D on plastic, on polyHEMA (pHEMA), and in 3D lrECM. Bar, 25 μm. (B) Western blot analysis of STAT5 phosphorylation in EpH4 cells 10 min after Prl treatment. EpH4 cells were cultured in 2D on plastic, on polyHEMA, and in 3D lrECM for 24 h. (C) Quantification of β-casein mRNA levels by real-time RT-PCR. EpH4 cells cultured on plastic, on polyHEMA, and in 3D lrECM were treated with Prl for 24 h before RNA extraction. The bar graph represents the mean ± SEM.