Abstract
The alleged modification of tumor cells by treatment in vitro with normal liver RNA, resulting in the greatly diminished cell transplantability (DeCarvalho and Rand, and Niu, Cordova, and Niu), was investigated in relation to the carcinostatic liver factor, which we previously reported.
It was found that the anti-tumor activity of our liver extracts was not affected in the least by digestion with pancreatic RNase, in spite of the fact that the RNA content of the extract was reduced almost to 10% by the RNase treatment. Without questioning the validity of the RNA effect claimed by other workers, therefore, we conclude that our carcinostatic liver factor may be totally unrelated to RNA.
