DLL4 and hepatocellular carcinoma: In addition, there is a research examining the intercellular crosstalk between HepG2 and endothelial progenitor cells (EPCs) in a co-culture system, which revealed that the expression of ephrin-B2, and Delta-like 4 ligand (DLL4) are upregulated in co-cultured EPCs and are associated with increased migration of HCC cells (136).