Fig. 6.

Extracellular ATP increases PI3K activity in VVEC. Growth-arrested cells DMEM were stimulated with ATP (100 μM) for 30 min. Equivalent amount of total cell protein (500–750 μg) was immunoprecipitated with rabbit polyclonal antibodies against the p85α regulatory subunit of PI3K, p110α, p110β, and p110δ catalytic subunits, or against the p101γ adaptor protein. PI3K activity was measured in in vitro kinase assay with a L-α-phosphatidylinositol (PtdIns) as a substrate. Arrow indicates the accumulation of a product of PI3K activity, PtdIns(3)P