Reduced ETRB expression does not alter the effect of ETRB antagonists on viable cell number. (A) ETRB mRNA in untreated cell lines. ETRB mRNA was not detected in the SW1088 line. (B) Following transfection, reduction in ETRB mRNA was assessed by real-time RT-PCR. Reduction in ETRB expression is displayed as a percentage relative to ETRB mRNA in cells transfected with scrambled siRNA. (C) Cells were transfected with either scrambled siRNA or ETRB siRNA and then treated with either 100 μM A-192621 or 100 μM BQ788 for 72 h. Values are expressed as a mean of three replicates ± SEM. Significance was determined by a paired t-test. Symbols for statistical significance are displayed at the bottom of the figure and are applicable to panels B and C.