Since CD31+NG2– vessels were more prevalent in hypoxic regions at the tumor edge than the tumor core and the lower MVD were measured at tumor core (Figure 1B), a possibility was raised that hypoxia at tumor core and edge is caused by different mechanism; the former is caused by vessel insufficiency (low MVD) while the latter is by vessel malfunction (CD31+NG2– vessels). The gene discussed is PECAM1; the disease is neoplasm.