Changes in sensitivity to cytotoxic agents occurring during the life history of monolayer cultures of a mouse tumour cell line.

Dose-response curves have been obtained for the response of EMT6 mouse tumour cells in vitro to adriamycin, actinomycin D, nitrogen mustard, BCNU and CCNU. The experiments have been carried out with exponentially growing cells and with cells in early and late plateau phase. The results are discussed with particular reference to discrepancies with the results obtained by other workers in similar systems