Calcium as a regulator of the proliferation of normal, but not of transformed, chicken fibroblasts in a plasma-containing medium.

In a culture medium of low calcium concentration containing 5% heat-inactivated chicken plasma, normal chicken fibroblasts divide very slowly, while their counterparts transformed with Schmidt-Ruppin Rous sarcoma virus divide much more rapidly. In the same low-calcium medium, the use of heat-inactivated serum, rather than heat-inactivated plasma, results in rapid division of both normal and transformed cells. The use of heat-inactivated plasma rather than serum, and the use of a low-calcium medium, combine to permit the demonstration of a marked difference between the proliferative behaviors of normal and neoplastic cells and suggest a basis for the autonomy of the latter.