Increase in S‐adenosyl‐L‐methionine decarboxylase activity during the transformation of chick embryo fibroblasts by rous sarcoma virus

The increase in S‐adenosyl‐L‐methionine decarboxylase activity in chick embryo fibroblasts after infection with Rous sarcoma virus has been studied. It has been shown that enzyme levels in transformed cells were two or three times higher than those of the non‐infected controls. The activity of this enzyme was not elevated in chick embryo fibroblasts infected with a temperaturesensitive mutant of Rous sarcoma virus (RSV‐T5) at 42°C, the non‐permissive temperature. When the temperature of these infected cultures was shifted from 42°C to 37°C a two‐ or three‐fold increase in decarboxylase activity was detected after 10 to 12 h. The half‐live of Sadenosyl‐L‐methionine decarboxylase was practically identical in normal and RSV‐transformed fibroblasts.