(A and B) – SiRNA-induced GFP silencing (A) and intracellular Cy3-siRNA levels (B). U-87-d1EGFP (A) or non-transformed U-87 cells (B) were treated with PAMAM/siRNA complexes at a final siRNA concentration of 100 nM for 4 hours under serum-free conditions. Cells were analyzed using flow cytometry for GFP fluorescence (A) or Cy3 fluorescence (B) 24 hours after the initial treatment. PolyFect (A) was used at 5:1 wt. ratio of PolyFect:siRNA. Data represent mean ± SEM (n = 3) (A) or (n = 1 experiment, measurements performed in triplicate) (B).