IL34 and neuroblastoma: Moreover, activation of toll-like receptors (TLRs) with pathogen-associated molecular patterns, such as peptidoglycan, lipopolysaccharide, and nucleic acid mimickers (e.g., CpG, poly I:C) promotes IL-34 expression in macrophages and intestinal LPMC, as well as in adipocytes, while stimulation with Iα,25(OH)2D3, a hormonally active form of vitamin D, increases IL-34 expression in neuroblastoma cells and normal gastric epithelial cells [24,26,27].