While our initial hypothesis was that GX15-070 interferes with Mcl-1 activity, but not necessarily modulates its expression levels, we found that GX15-070 by itself markedly reduced the expression levels of Mcl-1 in glioblastoma cells, which in turn would be expected to attenuate ABT263-mediated up-regulation of Mcl-1 and thus drive susceptibility of glioma cells to BH3-mimetics. Here, MCL1 is linked to central nervous system cancer.