Purification of colony-spreading stimulatory factor in calf serum.

Abstract

<p>Calf serum (19 ml) was used as the starting medium. To measure the colony-spreading stimulatory activity, samples were serially diluted 2-fold and applied to 20 ml of soft agar and incubated for 8 h at 37°C. The diameters of giant colonies were measured from each dish, and stimulatory activities were calculated.</p