Arginase II expression in mRCC cell lines. (A) After 48 hours in culture, CL-19 cells presented significantly more arginase activity (*P < 0.0001) than did either CL-2 or Renca cells. Similar results were found after 72 hours in culture. (B) Twenty five micrograms of protein were tested for arginase I and arginase II expression by Western blot analysis. Normal mouse liver and kidney were used as positive controls for arginase I and arginase II respectively, whereas GAPDH was used as house keeping protein. (C) Total RNA from CL-2, CL-19 and Renca cells were obtained by TRIzol extraction and 1 μg of RNA was tested for arginase I, arginase II, and β-actin by RT-PCR. DNA fragment sizes generated by RT-PCR: arginase I, 250 bp; arginase II, 310 bp; and β-actin, 436 bp. These data are from a single experiment that is representative of five separate experiments.