SCF-induced tyrosine phosphorylation of c-kit in normal and PV ECFC. Day-8 cells were incubated at 37°C for 10 minutes in medium or in medium with rhSCF at 100 ng/mL. The cells were then lysed and immunoprecipitated with anti-pTyr antibody. Western blotting was performed with anti-pTyr antibody (A) and the immunoblots were reprobed with antibody to c-kit (B). The purity of the ECFC was 69% ± 12% (normal) and 77% ± 10% (PV).