Kinetics of the development of MuSV-malignant cell transformation in the presence of Porphyridium sp. polysaccharide, dextran sulfate or carragenaan NIH/3T3 cells were infected with 105 ffu of MuSV-124 in the absence or presence of 10 μg/ml of Porhyridium sp. polysaccharide (■), dextran sulfate (◆) and carrageenan k (●). The treatment with the polysaccharide was continued up to the end of the experiment. Data are mean ± SD, (n = 4).