Phosphorus metabolism of a C3H ascites tumor in vitro.

The age of in vivocultures of ascites tumor cells was shown to determine in part the rate of labeling of phosphorus compartments of the cells (nucleic acids, phospholipides, and phosphoprotein) with P32 (7). During the course of this experimentation, the question arose whether this effect of age upon radioactive labeling resided in the cell itself or in the ascitic fluid bathing the cells in vivo. To test this hypothesis, it was necessary to study the labeling of ascites cells in vitro, where the ascitic serum and cells could be separated and the cells washed free of the bathing fluid and therefore of the influence of ascitic fluid upon the cell's metabo