Characterization of Tetraploid Cell Lines

All cell lines were maintained at 37°C with 5% CO₂ atmosphere. Immunofluorescence microscopy was performed as previously described 17 (link). Fixed cell images were collected by confocal immunofluorescence on a Yokogawa CSU-X1 spinning disk confocal mounted on a Nikon Ti-E inverted microscope (Nikon Instruments). Live-cell imaging was performed using a TE2000-E2 inverted Nikon microscope equipped with the Nikon Perfect Focus system enclosed within a temperature and CO₂-controlled environment that maintained an atmosphere of 37°C and 3-5% humidified CO₂. Sequential FACS sorting of tetraploids with 8c DNA content was used to generate tetraploid cells with two centrosomes. Detailed descriptions of FISH, karyotyping, imaging, cell lines, culture conditions, and antibodies used in this study can be found in supplementary methods.