Effect of hydrocortisone on arginase activity in ICRC mouse mammary tumours in vitro.

Three fold increase of arginase activity was observed in hydrocortisone treated mammary tumour tissue when compared to the untreated tissue in vitro. No change in succinic dehydrogenase activity was observed. It is likely that arginase present in mammary tumour is due to the presence of mammary tumour virus and it is tempting to speculate that the increase in arginase activity by hydrocortisone may be due to sustained viral production in the presence of hydrocortisone.