Characteristics of WI-38 cells (WI-38 CT-1) transformed by treatment with Co-60 gamma rays.

The characteristics of WI-38 CT-1 cells, which had been transformed by treatment with Co-60 gamma rays, were compared with those of the control WI-38 cells in order to identify parameters of malignant transformation in cultures of normal human diploid cells. The transformed WI-38 CT-1 cells were different from the control WI-38 cells in the following respects: (1) epithelial-like morphology of the cells, (2) reduced serum requirement for cell proliferation, (3) increased colony formation in soft agar, (4) increased saturation density, and (5) resistance to the cytostatic effect of theophylline on cell proliferation. On the other hand, no appreciable difference was detected between the control and the transformed cells in (1) population doubling time and (2) sensitivity to Co-60 gamma rays.