Fig. 5.

Interaction of PI3KAP/XB130 with PI3K is required for potentiation of DNA synthesis induced by IGF-I. NIH3T3 cells were infected with control retrovirus pMXs-neo (mock) or retrovirus encoding FLAG-PI3KAP/XB130 or FLAG-Y72F. A, The cell lysates were subjected to immunoprecipitation (IP) with anti-FLAG antibody. The immunoprecipitates and the total cell lysates were subjected to immunoblotting (IB) with indicated antibodies. B, The retrovirus-infected cells were serum starved for 24 h and then treated with 100 ng/ml IGF-I for 16 h. [Methyl-³H]thymidine incorporation into DNA was measured during the last 4 h. The means ± sem of three replicate wells are shown. There are significant differences between values with different letters (P < 0.05). Similar results were obtained in three independent experiments.