DLL1 and gastric cancer: There was also upregulation of genes encoding for the gastric cancer stem cell markers CD44, ALDH1 and CD133, as well as key stem cell pathways such as NOTCH and WNT., These included the notch ligand delta-like ligands (DLL-1 and DLL-4) and PLA2GA, an important regular of metastases in gastric cancer and expressed with constitutively active Wnt27–29.