Filing Date: 2000-07-17.-- Priority Data: GB 9916810 (1999-07-16).The present invention relates to killing cells, or at least impeding cell cycle progression. More particularly it relates to methods and means for attacking eukaryotic cells, such as tumour cells, with cytostatic, cytotoxic and/or cytopathic agents. Specifically, the present invention employs the ParD kid toxin and ParD kis antitoxin under appropriate control for selective cell cycle inhibition and/or killing of target cells.