Gene expression analysis of these cells revealed that COX2, heparin binding EGF like growth factor (HBEGF), and ST6 N-acetylgalactosaminide alpha-2,6-sialyltransferase 5 (ST6GALNAC5) were involved in brain metastasis of breast cancer by mediating cancer cell passage through the blood-brain barrier (BBB) [91]. The gene discussed is ST6GALNAC5; the disease is cancer.