Figure 3.

erbB-2 gene targeting in nonhuman cells. (A) Flow cytometric analysis of ErbB-2 expression. COS-7 fibroblasts were infected with E2C-KRAB-encoding retrovirus. Three days later, intact cells were stained with the ErbB-2 specific mAb FSP77 in combination with phycoerythrin-labeled secondary antibody, and analyzed by flow cytometry. (B) ErbB-2 Western blot. NIH 3T3 fibroblasts were mock-infected or infected with E2C-KRAB- or E2C-VP64-encoding retrovirus. Three days later, protein extracts were prepared and subjected to Western blotting with the ErbB-2-specific antiserum 21N. Mr, molecular weight × 10⁻³.