Third, we show that although MEFs with two distinct W-CIN defects efficiently reprogram into iPSCs, they do so with highly contrasting outcomes on chromosome number integrity and stability (Figure 6): our data suggest that BubR1 hypomorphic iPSC clones preferentially originate from aneuploid MEFs, while RanBP2 hypomorphic iPSC clones preferentially stem from MEFs with normal diploid chromosome numbers. Here, BUB1B is linked to cervical squamous intraepithelial neoplasia.