DLK or mitogen-activated protein kinase kinase kinase 12 is a transmembrane protein containing six epidermal growth factor repeats and is a serine/threonine protein kinase. DLK is involved in the differentiation of several cell types, including adipocytes. DLK plays a role of a tumor suppressor protein and is predominately expressed in neuronal cells. DLK as an activator of the Jnk pathway. Overexpression of DLK results in activation of Jnk1 and the accumulation of a hyperphosphorylated form of c-Jun (1). Postnatal loss of DLK in stem cells and niche astrocytes has been shown to regulate neurogenesis (2).