Energy costs of growth in continuous metazoan cell cultures.

One important contribution tissue culture can make, and still has to make, to cancer research is to define the cancer problem, to distinguish be tween normal cells and cancer cells in biochemical terms. Not long ago one of us set forth some of his ideas on the cause, nature, and prospective cure of cancer (4). The propositions advanced there be came the challenge for the experiments to be dis cussed hereinafter and the reasons for our start in tissue culture, which we prefer to call cell culture, for reasons which will soon become apparent. One of our propositions singled out the ubiquitous property of replicative growth as a cardinal at tribute of the cancer cell. This proposition stated further that the cancer cell is one which never matures or differentiates but unfailingly persists in an embryonic state. For the sake of brevity, we shall not here consider the question of how such cells originate, nor shall we reflect on whether the capacity to grow without cessation represents the gain or the loss of a cellular endowment. It is nec essary to emphasize, however, that we refer to cells and not to the aggregations of cancer cells called tumors. If a tumor appears to remain static in mass, it may mean that as many cells are dying as are being born. Our data may, on the other