Localization of endogenous Smad2 in HL-60 cells by confocal microscopy.

After 18-hour incubation with 10 ng/mL TGF-β1, 10 nM ATRA, or both, the cells were fixed, subjected to immunochemistry with primary antibodies against Smad2 and secondary antibodies linked to fluorescein isothiocyanate, and mounted with medium containing 4,6- DAPI. The red arrow indicates that Smad2 is localized both in the nucleus and in the cytoplasm. Original magnification for all panels, × 630. The result is representative of 3 similar experiments.