Furthermore, Watt et al. reported that N-myc positively regulates Mash1 transcription. Therefore, it is possible that in the transcriptional regulation of Mash1, LMO3 and HEN2 may associate with other nuclear factors like Insm1 and N-myc besides HES1. From the developmental point of view, it is known that the LMO/HEN complex plays an important role in regulating neuronal differentiation. As described, expression of LMO3 was highly restricted in adult and fetal brains, and HEN2 was expressed in developing nervous system. Genetic studies demonstrated that HEN2 participates in proper neural crestderived neuroendocrine development and that Mash1 has a critical role in maintaining neuroendocrine cell phenotype. Although LMO3-knockout mice did not exhibit any significant developmental defects, mice lacking both LMO1 and LMO3 died after birth, which might be due to neural defects. Since neuroblastoma is one of the most common childhood solid tumors of peripheral nervous system arising from as yet unidentified population of neural crest cells and Mash1 regulates proliferation of the CP-335963 sympathetic nervous system, it is likely that deregulated expression of Mash1 could contribute to genesis and development of neuroblastoma, which might be regulated by LMO3/HEN2 transcriptional complex both in vitro and in vivo. This LMO3/HEN2-HES1-Mash1 pathway could be the new future target for developing the anti-neuroblastoma treatment. The Michaelis-Menten kinetic parameters organized in Table 1, however, exhibit much higher Km values of this enzyme than the CP-226269 concentration of its natural substrates in cells. Based on its enzymatic characteristics, this enzyme would be inefficient in cells unless other associated protein could improve its efficiency. If the amount of this protein is changed or the protein is modified such as up-regulation, down-regulation, phosphorylation, dephosphorlyation, glycosylation and methylation, it should affect the metabolism of nucleotides in cells. No detailed study currently has yet addressed the role of this protein on nucleotide metabolism in cells. Deoxycytidine analogs and 5-Fluorouracil are used in clinic for the treatment of certain tumors and viral infections.