In vitro activity: XL184 has weak inhibitory activity against RON and PDGFRβ with IC50 of 124 nM and 234 nM, respectivey, and has low activity against FGFR1 with IC50 of 5.294 μM. XL184 at low concentration (0.1-0.5 μM) is sufficient to induce marked inhibition of constitutive and inducible Met phosphorylation and its resultant downstream signaling in MPNST cells, and inhibit HGF-induced MPNST cell migration and invasion. XL184 also induces marked inhibition of Met and VEGFR2 phosphorylation in cytokine-stimulated human umbilical vein endothelial cells (HUVECs). Although XL-184 has no significant effect on MPNST cell growth at 0.1 μM, XL184 at 5-10 μM significantly inhibits the MPNST cell growth.

Kinase Assay: Cabozantinib (XL184, BMS-907351) is a potent VEGFR2 inhibitor with IC50 of 0.035 nM and also inhibits c-Met, Ret, Kit, Flt-1/3/4, Tie2, and AXL with IC50 of 1.3 nM, 4 nM, 4.6 nM, 12 nM/11.3 nM/6 nM, 14.3 nM and 7 nM, respectively.

Cell Assay: Cells (ST88-14, STS26T, and MPNST724) are exposed to various concentrations of XL184 for 48 hours. Cell growth is determined by MTS assays using CellTiter96 Aqueous Non-Radioactive Cell Proliferation Assay kit. Absorbance is measured at a wavelength of 490 nm, and the absorbance values of treated cells are presented as a percentage of the absorbance of untreated cells.