C-fms (CSF1R) is located on the plasma membrane of the cell. C-fms is a receptor for ligand colony stimulating factor-1 (CSF1). C-fms is a complete transmembrane glycoprotein with ligand-induced tyrosine specific protein kinase activity that triggers signal cascades that ultimately affect the transcription of CSF1 reactive genes. Induction of c-FMS tyrosine phosphorylation after CSF1 binding leads to activation of Ras/Erk and IA phosphatidylinositol 3-kinase signaling pathways, which in turn activate signal transduction and transcriptional activators (STATs) pathways, specifically STAT1, STAT3, and STAT5. C-fms activation of CSF1 leads to increased growth, proliferation, and differentiation.