Fig. (8) The effect of silencing ERK1/2 on total cellular ATP pools and [14C]-glycine incorporation into ATP in parental and drug-resistant DU145 cells. Parental or drug resistant cells (1 x 104 per well) were plated in the absence or presence respectively, of 50 nM AG2034. After allowing 24 h to adhere, cells were transfected with ERK1/2 specific or non-specific siRNA probes. Resistant cells were continually maintained in the presence of drug. At hour 4, 0.63 µCi/ml of [14C]-glycine was added to the each well. Transient transfections lasted for a total of 34 h at which time TCA extracts from 24-pooled wells were used to quantify ATP levels by HPLC. Fractions corresponding to ATP were assayed for [14C]-glycine radioactivity by liquid scintillation counting. * and ** denote significant difference at P<0.001 and P<0.05 respectively, by students t-test. Data represent means ± S.D. of three independent determinations.