M-CSF (Macrophage Colony-Stimulating Factor), encoded by the CSF1 gene in humans, is a crucial cytokine that regulates the survival, proliferation, and differentiation of mononuclear phagocytes, including macrophages and their precursors. It binds to its receptor, CSF1R, activating signaling pathways essential for innate immunity, tissue homeostasis, and bone remodeling. M-CSF also plays roles in inflammatory diseases and cancer, where it can promote tumor-associated macrophage infiltration, supporting tumor progression. Its functions extend beyond hematopoiesis to include roles in metabolic regulation and neural development, making it a therapeutic target for conditions like autoimmune disorders and certain cancers.Besides,IL34 has been identified as an interactor of MCSF, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human MCSF and recombinant human IL34 . Briefly, biotin-linked MCSF were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100µl were then transferred to IL34-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST 3 times and incubation with Streptavidin-HRP for 30min, then wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50µl stop solution to the wells and read at 450nm immediately. The binding activity of MCSF and IL34 was shown in Figure 1, the EC50 for this effect is 0.09587µg/mL.