Immunofluorescent analysis of Estrogen Receptor alpha (ER alpha, green) in T47D and Hs 578T breast cancer cells. The cells were fixed with 4% paraformaldehyde for 15 minutes at room temperature, permeabilized with 0.1% Triton X-100 for 15 minutes at room temperature, and blocked with 0.3% BSA in PBS for at least 30 minutes at room temperature. Cells were stained with an ER alpha polyclonal antibody (Product # PA1-308) at a dilution of 1:4000 in blocking buffer overnight at 4C, and then incubated with a DyLight 488-conjugated goat anti-rabbit IgG secondary antibody (Product # 35552) at a dilution of 1:500 for at least 1 hour at room temperature. Nuclei (blue) were stained with DAPI (Product # 62247). Images were taken on a Thermo Scientific ToxInsight Instrument at 20X magnification.