Detection of iNOS mRNA in human B-CLL cells by RT-PCR. Total RNAs from 10 different human B-CLL cell samples (1 through 10) and from the A549 cell line, tested in two experiments A and B, were reverse transcribed and the cDNA obtained was submitted to 35 cycles of PCR in the presence of human iNOS specific primers, then analyzed by electrophoresis in a 7% acrylamide gel in the presence of BET, as described in Materials and Methods. MW, 1-kb ladder; A549, positive control; lanes 1 through 10, 10 different B-CLL cell samples (five in each panel A and B).