Fig. 1. Detection of overexpressed Rad51 protein in stably transfected cell lines by western blotting. (A) Human wild-type PPL and Rad51-overexpressing PPL928.1-2 cells. Total cell extracts were prepared from untreated and etoposide (etop.)-treated cultures. Equal amounts of total cellular protein were separated by electrophoresis and subjected sequentially to immunoblot analysis with antibodies to Rad51 and ß-actin. Antibody binding was quantified by densitometric analysis. The ß-actin signals were used to equilibrate the slightly different amounts of cell extract loaded per lane. Measurements from three independent western blot experiments were averaged. (B) Rat TGR and Rad51-overexpressing TGR928.1-9 cells. The amount of Rad51 in untreated wild-type (PPL or TGR) cells was chosen as a reference (100%).