Delta-like protein 1 is a type I transmembrane protein. The mature form consist of an extracellular domain of 528 amino acids (aa) that contain a DSL domain and eight tandem EGF repeats; the transmembrane region is 23 aa long and has a 155 aa cytoplasmic domain. After the binding of Notch receptors, the extracellular and cytoplasmic domains are cleaved, and the later is translocated into the cell nucleus to regulate gene expression. Delta-like protein 1 is expressed in heart and pancreas and in a lower amount in brain and muscle. During fetal life, it is transiently expressed during gastrulation and early organogenesis and its expression remains through adult life in hematopoietic tissues and the cortico-medullary region of the thymus.