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. Author manuscript; available in PMC: 2011 Aug 1.
Published in final edited form as: Future Oncol. 2010 Oct;6(10):1603–1624. doi: 10.2217/fon.10.116

Figure 4. Regulation of oncogenic c-Myc by protein phosphatase 2A via control of ceramide in normal and cancer cells.

Figure 4

In normal cells, ceramide and its binding protein, I2PP2A, which is the inhibitor for PP2A, are mostly in a 1:1 ratio. Therefore, it is believed to be the binding and inactivation of ceramide by I2PP2A that liberates the active form of PP2A, which, in turn, acts upon c-Myc, leading to the dephosphorylation and degradation. In cancer cells, elevated levels of I2PP2A were observed, which inhibits most of the available PP2A and results in stable (active) oncogenic c-Myc. The stable form of c-Myc can mediate tumor growth and cancer progression by upregulating expression of several oncogenes.

I2PP2A: Protein phosphatase 2A inhibitor 2; PP2A: Protein phosphatase 2A.