To understand the relationship between TMEFF2 methylation and the G-CIMP signature, we compared the TMEFF2 methylation status against the set of TCGA GBM samples with available G-CIMP and IDH1 mutation information. Of the TCGA samples analyzed by Noushmehr et al., 88 overlapped with the samples that we analyzed using the publicly available dataset. 76 of these were GCIMP- negative and 12 were G-CIMP-positive. All 76 G-CIMPnegative samples were negative for the IDH1 mutation, while all 12 G-CIMP-positive samples were positive for the IDH1 mutation. Strikingly, tumors with a greater than 0.1 TMEFF2 methylation beta value are found exclusively within the non-GCIMP and non-IDH1-mutant category. Thus, TMEFF2 does not belong to the reported G-CIMP loci; in contrast, there is a strong anti-correlation between TMEFF2 hypermethylation and G-CIMP-positive or IDH1 mutation status. That TMEFF2 hypermethylation is not found in the G-CIMP and IDH1-mutant GBM samples is consistent with our observation that higher levels of TMEFF2 are associated with the Proneural HGGs, the subclass that the G-CIMP tumors belong to, while suppressed expression of TMEFF2 is associated with the Proliferative and Sorafenib Mesenchymal subclasses of HGGs. Therefore, we further analyzed the relationship between TMEFF2 methylation status and the molecular subtypes of the TCGA GBM samples. Using an unsupervised approach to classify data from TCGA, Verhaak et al. described 4 GBM transcriptomal subtypes, termed Proneural, Neural, Mesenchymal and Classical. As recently reviewed in Huse et al., comparison of classification schemes of Verhaak et al. and Phillips et al. reveals a large degree of agreement in assignment of samples to Proneural and Mesenchymal subtypes, while the other expression subtypes are less well resolved. Therefore, we assigned ����Proneural���� only to those GBM samples that are classified as Proneural by both Phillips and Verhaak schemes, and ����Mesenchymal���� only to those classified as Mesenchymal by both schemes. All other samples are designated as ����Other����. As expected, TMEFF2 methylation beta values.0.1 are WY 14643 abmole almost exclusively observed in a subset of non-Proneural GBM samples, including both Mesenchymal and Other subtypes. Thus, TMEFF2 hypermethylation anti-correlates with the Proneural signature in GBMs. Consistent with the observation in HGG samples shown above, Proneural GBMs express the lowest levels of PDGF-A, compared to other GBMs. Moreover, a strong anti-correlation also exists between PDGF-A and TMEFF2 expressions in the TCGA GBM samples. Follistatin domain�Ccontaining proteins have been shown to interact with growth factors or their binding partners and modulate their signaling. For example, the follistatin domain�Ccontaining ECM�Cassociated glycoprotein SPARC/osteonectin was reported to interact with PDGF-AB and BB and inhibit the binding of these ligands to their cognate receptors on fibroblasts.