Abstract
A fetal-calf-serum component was isolated that stimulates [baby hamster kidney] cells in culture to adopt typical fibroblast morphology. This spreading factor is a glycoprotein with MW of about 62,000 and contains 12% carbohydrate; it has an isoelectric point of 4.8. The method described allows purification to homogeneity as judged by sodium dodecyl sulfate/polyacrylamide-gel electrophoresis and analytical isoelectric focusing. Under cell-culture conditions the factor is active at 18 .mu.g/ml.