Effect of increasing concentrations of vanadate on growth factor-induced protein tyrosine phosphorylation in normal (A) and PV (B) ECFC. Day-8 cells were incubated with increasing concentrations of vanadate for 1 hour at 37°C and were then exposed to rhEP at 20 U/mL and rhSCF at 100 ng/mL for 10 minutes at 37°C. The cells were lysed and then immunoprecipitated and immunoblotted with anti-pTyr antibody. The purity of the normal ECFC was 73% ± 2% and the purity of the PV ECFC was 78% ± 5%.