CD109 and astrocytoma (excluding glioblastoma): CD109 was significantly overexpressed in glioblastomas (grade IV) compared with lower grade astrocytomas (grades II–III) (P = 0.007) (Figure 1B and Supplemental Table 1; supplemental material available online with this article; https://doi.org/10.1172/jci.insight.141486DS1).