(A) PC3 cells were cultured under normoxic or hypoxic conditions for 24 hours and were tested for IL-11Rα expression by flow cytometric analysis as described in the Methods. (B) Left: PC3 cells were serum starved for 24 hours and then incubated in normoxia for the indicated times in the presence of 100 ng/ml of rhIL-11. Right: Serum-starved PC3 cells were cultured in normoxia or hypoxia for 48 hours in the absence or presence of a human IL-11–neutralizing antibody (50 ng/ml) or an isotype-matched control antibody (IgG). Levels of pSTAT1 (Tyr701 and Ser727), pAKT (Ser473), and pSTAT3 (Ser 727 and Tyr705) were assessed using Western blot. Results shown are representative of 2 independent experiments. C, untreated control; +, positive control. (C) PC3 NC, IL-11KD#1, and IL-11KD#2 cells were cultured under normoxic or hypoxic conditions for 24 hours and then plated in soft agar. Results shown are the average of 2 independent experiments (t test; *P < 0.05). (D) PC3 NC, IL-11KD#1, and IL-11KD#2 cells were cultured under normoxic or hypoxic conditions for 24 hours and then plated. Colonies were stained after 10 days (mean ± SEM of 2 independent experiments). (E) PC3 NC, IL-11KD#1, and IL-11KD#2 cells were cultured as described for the right panel of B. Levels of total and phosphorylated ERK, AKT, p38, and STAT1 were measured using immunoblotting. (F) PC3 lysates were analyzed as described in E. Results are representative of 3 experiments.