a GUSB probe was confirmed by a GAPDH probe. The relative expression level of each sample was comparable. c MYC expression was also upregulated upon stimulation download catalog with NGF in imatinib treated cells in the absence of serum, however, its expression level was lower than that in Table 2 PANTHER analyses of c Kit versus NGF regulated genes which are involved in immune related function in HMC 1 cells imatinib untreated cells with serum. To examine whether high c MYC expression in untreated cells is due to the activated c Kit kinase and or serum which may contain activation factor of the c MYC gene, we performed c MYC specific qRT PCR in the pre sence of serum with imatinib and or NGF. Imatinib suppressed c MYC expression about 70% even in the presence of serum, suggesting that activated c Kit induces c MYC expression.

However, in the presence of serum, NGF induces c MYC expression 2 fold more than in the absence of serum, suggesting that serum and c Kit or TrkA tyrosine kinase synergistically induce c MYC expression. Furthermore, 32 genes, including c MYC, EGR1, EGR2, HES1, and KLF2 of 58 genes that were downmo dulated by imatinib and upregulated upon stimulation with NGF are involved in survival and proliferation, sug gesting that NGF TrkA signaling may take over the sur vival and or mitogenic signal in the imatinib treated HMC 1 cells using these genes. Novel target genes, KLF2, and SMAD7 which were induced by NGF TrkA signaling are involved in anti apoptosis signal in hematopoietic cell system Expression profiling of NGF TrkA induced genes is well documented in neuronal cell systems.

However, there is no information about profiles of genes induced by NGF TrkA signaling in a hematopoietic cell system. We therefore compared our upregulated genes to known NGF targets in neuronal cells. Several genes, such as the recently demonstrated ATF3, KLF10, and v maf muscu loaponeurotic fibrosarcoma oncogene family protein F were found to be induced Entinostat in our array. In addition to the above, we show for the first time the upregulation of potential novel TrkA target genes such as KLF2, SMAD7, and Homeobox members, HOXB8 and PBX2, upon NGF stimulation in HMC 1 cells. Since it has been shown that an immediate early gene product, KLF2 activates SMAD7 expression, we examined the upregulation of KLF2, SMAD7 and EGR1 by RT PCR.

In agreement with array data, KLF2 was upregulated within 30 min similar to the EGR1 gene, however, SMAD7 was upregulated in 2 h, sting that KLF2 may be the direct target gene merely of NGF TrkA signaling, but not SMAD7. We next asked whether KLF2 and SMAD7 are targets of c Kit signaling. Since oncogenic c Kit is not fully activated, SCF treatment is able to induce further upregulation of c Kit mediated signaling. HMC 1 cells were grown in the absence of serum for 17 h, and were then sti mulated with SCF. The expression of KLF2, SMAD7 and EGR1 was then examined by RT PCR. All three genes were upregulated by stimulation with SCF. It should be noted that KLF2