COL1A2 and gliosarcoma: When compared to GBMs, gliosarcomas show up-regulation of some genes, ranging up to a 6-fold difference on a log2-scale (Figure 4C) and most top differentiating genes encode collagens (COL1A1, COL6A1, COL6A2, COL6A3, COL1A2, COL3A1) (Figure 4C).