Knock down PIK3R3 by siRNA (sc-39124, Santa Cruz) inhibited the growth of HGC27 GC cells. (A) PIK3R3 mRNA level in 4 GC lines measured by quantitative RT-PCR, and the relative PIK3R3 mRNA level was calculated by comparison against KATO III. Shown are the mean +/− s.d. of triplicate samples. (B) Western blot of PIK3R3 knockdown in transfected cells. (C) Cell number (measured by optical density (O.D.)) after knockdown by PIK3R3 siRNA. (D) DNA synthesis (BrdU incorporation) after knockdown of PIK3R3. The data in these experiments are expressed as means ± S.D. from three independent experiments. The significance was assessed by paired student’s t-test. *P < 0.05 comparing knockdown with control. (E) Cell death measured by Annexin-V/PI staining.