FIG. 6.

Ectopic expression of clusterin inhibits PI3K-Akt activation and cell proliferation. (A) The empty control (Con) vector or the clusterin-expressing plasmid (Clu) was transfected into HEK293T cells. The resulting serum-free CM (30 h) fractions were analyzed for clusterin expression (left) and their abilities to affect the Akt phosphorylation in NB4 cells (right). (B) The Con- or Clu-containing HEK293T-CM samples were mixed (1:1) with HeLa-CM and left untreated or were heat treated and tested for their abilities to affect HeLa-CM-mediated Akt phosphorylation in NB4 cells. (C) Effects of clusterin on HeLa-CM-elicited Akt phosphorylation in HEK293 cells. (D) The Con- or Clu-containing HEK293T-CM was mixed (1:1) with different amounts of serum and added to HEK293 cells in triplicate. Cell proliferation was measured by MTT assay after 72 h. Results are the means ± standard errors of three independent experiments.