Frequency of spontaneous neoplastic transformation in bystander cells.

Neoplastic transformation frequency in the progeny of bystander C3H 10T½ MEFs assayed 10 population doublings after they had been in co-culture with 1 GeV/nucleon iron ion- or sham-irradiated MEFs. Data from each independent experiment are shown separately. For each of the 3 experiments shown and for their sum, the transformation frequency per viable cell (± standard error, SE), per cell at risk, and using the null method (± standard error of the mean, SEM) is indicated. Relative to control, progeny of bystander C3H 10T½ MEFs that had been in co-culture 10 population doublings earlier with MEFs irradiated with 25 cGy from 1 GeV/nucleon iron ions showed an increased frequency of spontaneous neoplastic transformation.