Delta-like protein 1 (DLL1) is also known as Drosophila Delta homolog 1 (Delta1 or H-Delta-1), which contains one DSL domain and eight EGF-like domains. DLL1 is ubiquitinated by MIB (MIB1 or MIB2), leading to its endocytosis and subsequent degradation. As for expression, DLL1 is expressed in heart and pancreas, with lower expression in brain and muscle and almost no expression in placenta, lung, liver and kidney. Furthermore, DLL1 acts as a ligand for Notch receptors. Also, DLL1 can block the differentiation of progenitor cells into the B-cell lineage while promoting the emergence of a population of cells with the characteristics of a T-cell/NK-cell precursor.