BRAF gene duplication constitutes a mechanism of MAPK pathway activation in low-grade astrocytomas
J. Clin. Invest. Stefan Pfister, et al. 118:1739 doi:10.1172/JCI33656 [Go to this article.]

Figure 2
BRAF and CCND1 expression in primary pilocytic astrocytomas. (A) BRAF mRNA expression levels in 5 pilocytic astrocytomas with 2 copies of BRAF (left) and 8 pilocytic astrocytomas with 3 copies of BRAF due to gene duplications (right) in relation to the BRAF transcript levels in nonneoplastic brain tissue. Note that the median BRAF mRNA expression level is significantly higher in tumors with BRAF duplications as compared with tumors without this aberration (P = 0.01). (B) CCND1 mRNA expression in the same tumors. Median CCND1 mRNA expression levels are significantly higher in tumors with BRAF duplications than in tumors with 2 gene copies (P = 0.008). (C) Western blot analysis demonstrating BRAF protein expression (upper panel) and ERK1/2 phosphorylation (pERK1/2, middle panel) in 6 tumors with BRAF duplication (lanes 2–7) and in nonneoplastic brain tissue (lane 1, pooled protein fractions from 5 brain tissue samples from 5 different individuals) showing that BRAF is exclusively expressed in the tumors and always associated with activation of MAPK signaling. Total ERK1/2 protein was used as a loading control (ERK1/2, lower panel). nb, normal brain; PA, pilocytic astrocytoma.