To determine if changes in sister chromatid cohesion correlate with increased aneuploidy in mouse retinoblastoma cells, we analyzed the distance between sister chromatids in colcemid-treated mouse retinoblastoma tumor cells from RbTKO, MDMX and p53TKO strains and the SJmRBL8 mouse retinoblastoma cell line. Here, MDM4 is linked to retinoblastoma.