Fig. (3) The effect of AG2034 on cellular ATP pools and [14C]-glycine incorporation into ATP in DU145 prostate cancer cells maintained in 0HPX media. Parental or drug-resistant DU-145 cells (1 x 106) were plated in 0HPX media and allowed 48 h to adhere to plates. One group of parental cells (Column I) was maintained in 0HPX media and exposed to 0.8 µCi/ml of [14C]-glycine for 24 h. A second group of parental cells (Column II) was simultaneously exposed to 50 nM AG2034 and 0.8 µCi/ml of [14C]-glycine for 24 h. A third group (Column III) consisted of resistant cells which had been maintained in the continual presence of 50 nM AG2034, also had 0.8 µCi/ml of [14C]-glycine added. At the 24 h time point, ATP levels were determined from TCA extracts and quantified by reverse-phase HPLC. After 24 h, the nucleotide fractions corresponding to ATP were collected and assayed for [14C]-glycine radioactivity by liquid scintillation counting.