Ki-20227 is a specific c-Fms tyrosine kinase(CSF1R) inhibitor (IC50: 2 nM). It also has certain inhibitory against VEGFR2(IC50: 12 nM) and c-Kit/PDGFRβ(IC50: 451/217 nM), respectively.

VEGFR2:12 nM, CSF1R:2 nM

Ki20227 hasn't inhibition for other kinases tested, such as EGFR, Fms-like tyrosine kinase-3, or c-Src (c-src proto-oncogene product). Ki20227 also inhibits the M-CSF-dependent growth of M-NFS-60 cells but not the M-CSF-independent growth of A375 human melanoma cells in vitro. Ki20227 has an inhibition against M-CSF-dependent reactions, such as lipopolysaccharide-induced TNF-α production, which was enhanced by M-CSF in vitro.

Ki20227 reduces the number of tartrate-resistant acid phosphatase-positive osteoclast-like cells on bone surfaces in ovariectomized (ovx) rats. Furthermore, in the Ki20227-treated mice, the number of CD11b(+), Gr-1(+), and Ly-6 g(+) cells in the spleen were decreased and the CII-induced cytokine production in splenocytes isolated from the Ki20227-treated arthritic mice was also reduced. In EAE animal model, Ki20227 inhibits the turn-over/expansion of myeloid cells provoked by the immunization and subsequent MOG-specific T cell responses.