Interleukin 34 (IL-34) is a 23.98 kDa cytokine with 216 amino acid residues. IL-34 is a ligand of the colony-stimulating factor 1 receptor (CSF-1R) and is mainly secreted from the adrenal, frontal lobe, and cortex. IL-34 play a vital role in the proliferation, survival, differentiation, and migration of myeloid cells. These functions are mediated by IL-33 activating ERK1 /2, JAK, and PI3K/AKT signal pathways.