Western blot analysis for detection of ERG protein in cell lysates. A. A 55 kDA band corresponding to ERG protein was observed in HEK293 cell lysates spiked with purified recombinant protein in all lanes except the HEK293 only sample. GAPDH was used as a loading control. B. The limit of detection was 0.195 ng of ERG protein in western blot analysis. C. Cell mixtures containing VCaP and LNCaP cells, kept constant with 100,000 total cells, revealed that 10,000 VCaP cells are detected by western blot. GAPDH was again used as a loading control.