Choline kinase (ChoK) is a vital enzyme that involved in the ras signaling pathway by converting the choline into phosphorylcholine (PCho) and the overexpression of PCho can potentially lead to carcinogenesis.   In mammalian cells, ChoK exists in three isoforms (ChoK-a1, a2 and b) that are encoded by two separate genes termed, as ChoK- a and ChoK-b and these isoforms are active either in homo- or hetero-dimeric or in oligomeric forms. The ChoK also carries the ethanolamine kinase activity in several organisms, whereas in lower eukaryotes, these activities are associated with distinct enzymatic entities. PCho is one such important lipid metabolite that is involved in the cell proliferation as well as in tumor production. 
In cells, the PCho level is regulated by ChoK along with PLD through the Kennedy pathway. The overexpression of PCho is associated with the higher activation of ChoK and it has been reported that various growth factors namely, platelet-derived growth factor (PDGF), epidermal growth factor (EGF), insulin dependent growth factor (IDGF), vascular endothelial growth factors (VEGF) etc., enhance the ChoK activity during the tumor production. Importantly, Ras signaling pathway through its two well-known effectors, Ral-GDS and PI3K produces essentially the same effect of enhancing the ChoK activity during the tumor formation. However, decrease in ChoK activity when treated with its inhibitors, in the ras transformed cells, unambiguously establishes the ras arbitrating role in ChoK activation during the tumorigenesis.

References

1.Janardhan S,et al. Curr Med Chem. 2006;13(10):1169-86.