Evaluation of the spindle assembly checkpoint dysfunction in triggering chromosomal instability of pRb-depleted cells. A) Expression levels of genes involved in cell cycle regulation, centrosome duplication and mitosis progression by TaqMan Low Density Array (TLDA). The x-axis indicates genes and y-axis the relative quantification in IMR90 cells untransfected (untr.) and transfected with siRNA targeting RB (siRB). B) Bar graphs showing increased mitotic index in untransfected (wt) and pRb-depleted (siRB) IMR90 cells after colcemid treatment (colcemid 8 h and 16 h). C) Immunofluorescence analysis detected Mad1 localization (green spots) in both wild-type and pRb-depleted cells after colcemid treatment (colcemid treated, a' and b' respectively) but not in untreated wild-type and pRb-depleted cells (untreated, a and b respectively). Nuclei were counterstained with DAPI (blue).