Hypothetical role of DAP12 in myeloid cell and oligodendrocyte development. In homeostatic conditions, the TREM-2 receptor may trigger the DAP12 signaling pathway in immature oligodendrocytes and osteoclasts, promoting their differentiation into mature cells capable of myelination and bone resorption, respectively. During inflammatory conditions, DAP12 may be solicited by different receptors, leading to differentiation and/or activation of microglial cells, macrophages, and DCs. While oligodendrocytes are thought to derive from a neuroepithelial progenitor, it is possible that DAP12-expressing oligodendrocytes may be of myeloid origin.