Figure 6.

Specific inhibition of PP2A is involved in the CAN-induced proliferation of QBC939 cells. (A) The phosphorylation of IKKα/IκBα/NF-κB-associated proteins was increased by OA (1 nM), as measured by western blotting. (B) PP2A activity and (C) cell viability were suppressed in cells treated with OA. (D) PP2A activity and (E) cell viability were upregulated in a dose-dependent manner in cells treated with DES (10 nM), a specific activator of PP2A. Data are expressed as the mean ± standard deviation. *P<0.05, **P<0.01 vs. control; ^#P<0.05, ^##P<0.01 vs. CAN. CAN, cantharidin; DES, D-erythro-sphingosine; NF-κB, nuclear factor-κB; IKK, inhibitor of NF-κB kinase; IκBα, NF-κB inhibitor α; OA, okadaic acid; p, phosphorylated; PP2A, serine/threonine-protein phosphatase 2A.