Accelerated regeneration of trypsin-treated surface antigens of simian virus 40-transformed BALB/3T3 cells induced by X-irradiation.

The antigens of SV40-transformed BALB/3T3 cells measured by a radioisotopic footpad assay after removal by trypsin treatment regenerated in vitro in 3 to 6 hr. After X-irradiation with 3000 R, however, the antigens were regenerated to normal levels within 1 h. X-ray doses of between 1000 and 5000 R accelerated the regeneration of cell surface antigens, while X-irradiation with the larger dose of 8000 R did not. X-irradiation of nontrypsinized tumor cells was without effect. Possible mechanisms of this phenomenon are discussed.