The tumour promoter TPA does not affect mutation to ouabain resistance in L5178Y mouse lymphoma cells

: Following treatment with ultraviolet light or ethyl methane-sulphonate mouse lymphoma L5178Y cells were cultured for different periods in the presence of non-toxic levels of the tumour promoter 12-O-tetra-decanoylphorbol-13-acetate (TPA). There were no significant changes in either the spontaneous or induced frequencies of ouabain-resistant variants recovered after TPA treatment. These results confirm that any effect of TPA on mutagenesis may be by modifying metabolic cooperation and the recovery of resistant cells.