CSF1R and neoplasm: Among 20 RTK subfamilies, RTK class III (PDGFR family) which includes PDGFRα, PDGFRβ, C-KIT, CSF1R, and FLT3, is highly expressed in various types of epithelial cancers9 and associated with poor prognosis11,12 via promoting tumor angiogenesis and metastasis1,6,12.