High content cell-based genetic and small molecule library screens are powerful strategies in drug discovery and investigations of disease mechanisms. We report that primary cells derived from a transgenic mouse model expressing a fluorescence mitosis biosensor provide unambiguous phenotype readouts without the need for transfection or immunocytochemistry. Phenotype profiles of cell cycle disruption and of apoptosis are easily detectable at a single time point selected from time-lapse live fluorescence microscopy. Most importantly, this transgenic mouse model may be crossed with cancer mouse models to derive biosensor-expressing primary cancer cells for use in high content screening strategies targeting discovery of tumor-specific chemotherapeutic compounds.