Figure 8. Schematic illustration showing how Pygo2 inhibits the efficacy of PTX-induced apoptosis in human glioma cells.

PTX treatment of cells causes a series of apoptotic responses, including phosphorylation of Bcl-2, activation of caspase-8/9, and activation of the JNK pathway, which were inhibited by over-expression of exogenous Pygo2 (Left). Cells also exhibited an increased expression level of MDR1. P-gp acts as an efflux pump that pumps the PTX granules out of cells, and up-regulated expression of P-gp further mediates PTX resistance. Over-expression of exogenous Pygo2, which occupies the promoter of MDR1, enhances the expression of P-gp to strengthen the multidrug resistance (Right).