Senescent human breast fibroblasts attenuate mammary epithelial alveolar differentiation. (A) MCF-10A cells co-cultured with presenescent (Presen, left) or senescent (Sen, right) hBFs in 3D on Matrigel. Low (40×, upper panels) and high (100×, lower panels) magnifications of the cultures are shown. (B) α6 integrin immunostaining (green) of MCF-10A cells co-cultured on Matrigel with presenescent (Presen, left) or senescent (Sen, right) hBFs. Nuclei were counterstained with DAPI (blue); images shown at 200× magnification. (C) E-cadherin immunostaining (green) of MCF-10A cells co-cultured on Matrigel with presenescent (Presen, left) or senescent (Sen, right) hBFs. Nuclei were counterstained with DAPI (blue); images shown at 1000× magnification. (D) GM-130 immunostaining (green) of a representative MCF-10A alveolus co-cultured on Matrigel with presenescent (Presen, left) or senescent (Sen, right) hBFs. Nuclei were counterstained with DAPI (blue). Merged images show the apical polarity of GM130; images shown at 400× magnification. (E) Tubulin (green) and actin (red) immunostaining of representative MCF-10A alveoli co-cultured on Matrigel with (Presen, left) or senescent (Sen, right) hBFs. Nuclei were counterstained with DAPI (blue), and images shown at 400× magnification.