PI3K inhibition decreases cellular proliferation and overcomes the protective effects of PDE4B2 expression. DHL6-PDE4B2-WT or DHL6-PDE4B2-PI cells were incubated with 10 μM of the PI3K inhibitor LY249002 and/or 10 μM forskolin for 24 hours, and cell proliferation was determined by MTS assay. Data represent the means and SDs of 3 independent assays.