Table 1.

Enzymatic Ki and cellular IC50 values determined by receptor phosphorylation assays

TargetRTK phosphorylation, IC50 (nmol/L) ± SD
ELISA*Immunoprecipitation/immunoblotting
VEGFR-2 (KDR)0.20 ± 0.06 (VEGFR-2/PAE)0.06 (HUVEC)
VEGFR-1 (Flt-1)ND∼0.1 (HUVEC)
Murine VEGFR-2 (Flk-1)0.18 ± 0.03 (Flk-1/NIH-3T3)ND
VEGFR-3ND0.1∼0.3 (VEGFR-3/PAE)
PDGFR-β1.6 ± 0.4 (PDGFR-β/PAE)2.9 (NIH-3T3)
PDGFR-α5.0 ± 1.0 (PDGFR-α/NIH-3T3)ND
KIT1.7 ± 0.6 (KIT/PAE)0.98 (NCI-H526)
CSF-1R73 ± 18 (CSF-1R/NIH-3T3)ND
Flt-3>1,000 (RS;411)ND
  • * Abbreviation: ND, not determined.

    Measured in the presence of 0.1% FBS.

  • Measured in the presence of 1% FBS (HUVEC) or 0.1% FBS (PAE or tumor cells).

  • Measured in the presence of 1% FBS and 2.3% bovine serum albumin. Data were corrected for protein binding with the consideration that the presence of 2.3% bovine serum albumin typically shifted cellular IC50 values up by a factor of ∼10.