COL4A1 and glioblastoma: Similar to SERPINE1 and FN1, the expression of many other well-known TGFβ downstream targets was significantly upregulated in glioblastoma (grade IV) compared to grade III glial tumors, and they are highly correlated with SERPINE1 (Additional File 1), including TGIF (p < 1.11 × 10-8, r = 0.57), VEGF (p < 7.57 × 10-7 r = 0.63), THBS1 (p < 0.005, r = 0.80), TIMP1 (p < 2.5 × 10-7, r = 0.80), COL4A1 (p < 1.7 × 10-7, r = 0.62), COL1A2 (p < 8.88 × 10-7, r = 0.69) [20,36-38].