Fig. 3. AZI expression increases ODC activity in AT2.1 and NIH-3T3 cells. (A) ODC activity (pmol ¹⁴CO₂/mg protein/hour) was measured in control and AZI-overexpressing AT2.1 cells, using [1-¹⁴C]-L-ornithine as the substrate. Total cell lysates were collected 24 hours after plating 5x10⁵ cells in medium containing 10% serum. Error bars indicate s.e.m. (B) Effect of AZI overexpression on cellular ODC activity in NIH-3T3 fibroblasts. ODC activity was measured as above. (C) Polyamine uptake by AZI-overexpressing cells was measured following a 15 minute incubation with 0.25-10 µM [¹⁴C]spermine, as described in the Materials and Methods. No significant difference was observed in spermine uptake between AT2.1 vector control () and AZI-overexpressing cells (). Error bars indicate s.e.m.