Immunofluorescent analysis of PKR (green) showing staining in the cytoplasm and nucleus of MCF-7 cells (right) compared to a negative control without primary antibody (left). Formalin-fixed cells were permeabilized with 0.1% Triton X-100 in TBS for 5-10 minutes and blocked with 3% BSA-PBS for 30 minutes at room temperature. Cells were probed with a PKR polyclonal antibody (Product # PA1-990) in 3% BSA-PBS at a dilution of 1:100 and incubated overnight at 4ºC in a humidified chamber. Cells were washed with PBST and incubated with a DyLight-conjugated secondary antibody in PBS at room temperature in the dark. Actin was stained using Alexa Fluor 554 (red) and nuclei were stained with Hoechst or DAPI (blue). Images were taken at a magnification of 60x.