COL6A3 and gliosarcoma: Collagens type I (COL1A1, COL1A2), III (COL3A1) and VI (COL6A2, COL6A3) were highly upregulated in gliosarcomas, as seen in Figure 4C. The collagen-signature is reflected in the functional analysis of the groups of genes differentially expressed between GBMs and gliosarcomas, as “focal adhesion” is one of the discriminating groups (Table 3).