In Schwann cells but not in epithelial cells, TGFβ treatment triggers Ski and Rb localization into the cytoplasm. (A–C) Coimmunostaining of Ski (red) and Rb (green; A) or Ski (red) and ser780pRb (pRb; green; B) in rat Schwann cells or WB-F344 cells (C) cultured in DM or treated with TGFβ for 48 h. Nuclei are labeled with DAPI (blue), and each picture represents the overlay of Ski and DAPI (appears pink when Ski is nuclear), Rb, or ser780pRb and DAPI (appears turquoise when Rb or ser780pRb is nuclear). (D and E) Western blot of Ski and ser780pRb (pRb) in cytoplasmic (C) and nuclear (N) fractions of rat Schwann cells (D) and WB-F344 cells (E) cultured in DM (set to 100%) or treated with TGFβ for 48 h. GAPDH and lamin were used as loading and fractionation controls for the cytoplasmic and nuclear fractions, respectively. Statistical analyses were performed using two-tailed t tests on at least three independent experiments. D, n = 5; E, n = 3. (F) BrdU (green) labeling and overlay of BrdU and ser780pRb (red) immunostaining in rat Schwann cells treated with TGFβ for 48 h (double stain appears yellow). (G) Images of single confocal sections of coimmunostaining of Ski (green) or ser780pRb (pRb; green) with EEA1 (early endosome marker; red) or P4D1 (ubiquitin; red) in rat Schwann cells treated with TGFβ for 48 h. Arrows indicate examples of the colocalization (appears yellow) of Ski or ser780pRb with EEA1 or P4D1. Insets are magnifications of the regions outlined by boxes. Error bars represent SEM. *, P < 0.05; **, P < 0.01; ***, P < 0.001.