Glutamine is an essential amino acid in cancer cells and is required for the growth of many other cell types. Glutami-nase activity is positively correlated with malignancy in tumours andwith growth rate in normal cells. In the present work, Ehrlich ascites tumour cells, and their derivative, cells, expressing antisense glutaminase mRNA, were assayed for apoptosis induced by methotrexate and hydrogen peroxide. It is shown that Ehrlich ascites tumour cells, expressing antisense mRNA for glutaminase, contain lower levels of glutathione than normal ascites cells. In addition, cells contain a higher number of apop-totic cells and are more sensitive to both methotrexate and hydrogen peroxide toxicity than normal cells
