Rather than via their shared ability to induce histone hyperacetylation. Subsequent analysis of histone modification distributions on VPA-responsive genes showed that, irrespective of transcriptional response, histone acetylation at gene promoters does not reflect the inhibitor-induced increase in bulk histone hyperacetylation. Even after longer inhibitor treatments, of the eight genes examined only one, DLK1, showed a modest increase in H4 acetylation. This is a small sample, but includes all the genes that show the largest transcriptional responses to HDACi treatment, suggesting that our findings are representative of most genes. It seems that local levels of histone acetylation are determined by gene specific factors rather than induced changes in global histone modification. While there are examples of individual promoters that fail to show enhanced acetylation in response to HDACi, they have been seen as counterintuitive exceptions, and most reports focus on increased histone acetylation in response to HDACi. This remains controversial, as a recent study found HDACi induced transient increases in promoter acetylation at a subset of genes, but deacetylation after prolonged exposure was a more typical response. Our data is consistent with this, and BAY-60-7550 suggests that many promoters show minimal change in response to HDACi and that genes showing increased acetylation, such as the Hoxb genes are the exception rather than the rule. Signal Transducer and Activator of Transcription 3 belong to the STAT family of transcription factors. Compelling evidence has now established that aberrant STAT3 is a molecular abnormality that has a critical role in the development and progression of not only adult but also some pediatric tumors. In addition to its diverse biological functions including roles in cell proliferation, differentiation, apoptosis, inflammation, and oncogenesis, accumulating evidence suggests that STAT3 also plays an important role in cancer angiogenesis under both physiological and pathological situations. There is accumulating evidence that STAT3 is an important facilitator of tumor angiogenesis and its activation correlates with VEGF production in a variety of human cancers. In addition to its effects on VEGF, STAT3 has been implicated as a facilitator of angiogenesis by other mechanisms. For example, it has recently been demonstrated that STAT3 regulates expression of both MMP-2 and MMP-9, important facilitators of both angiogenesis and metastasis. It has been reported also that STAT3 is required for endothelial cell migration and microvascular tube formation. LLL12 is a novel small molecule allosteric inhibitor of STAT3, thought to bind STAT3 monomers at the tyrosine 705phosphorylation site and to prevent dimerization and activation. Previous work has established that LLL12 inhibits proliferation of various cancer cells in vitro, and tumor growth of both breast and glioblastoma xenograft models. Moreover, LLL12 induces apoptosis in medulloblastoma and glioblastoma cells and was also able to inhibit colony formation, wound healing and decreased IL6 
and LIF secretion. Antisense STAT3 oligonucleotide or STAT3 inhibitors, other than LLL12, have been shown to reduce microvessel density in tumor models. However, the mechanism for these anti-angiogenic effects has not been investigated. Our current work shows that at concentrations of drug that abrogate STAT3 phosphorylation, LLL12 blocks angiogenesis, and suppresses tumor vasculature in osteosarcoma tumors. The Adriamycin direct effect of LLL12 suppressing proliferation of HIVEC and HASMCs was shown at low concentrations of drug that completely suppressed VEGF-stimulation of STAT3 phosphorylation.