Coomassie brilliant blue-stained polyacrylamide gel of procaryotically expressed vIL-6. The apparent molecular weight of vIL-6 observed here is 24 kD, which is in agreement with the calculated molecular weight of 22.6 kD. M, molecular weight marker; lane 1, 4 μg vIL-6, eluted from Ni-NTA with 200 mmol/L imidazole; lane 2, 2 μg of the same protein preparation as lane 1 after dialysis.