While there may be numerous defects that lead to CIN in a tumour, loss of Mad2 is found as a contributing factor in a range of CIN cancers [26], [27] and more than 80% of colorectal cancers carry APC mutations that have been shown to sequester Mad2 [28] and BubR1 [29] at least in some cell lines [30]. The gene discussed is BUB1B; the disease is cervical squamous intraepithelial neoplasia.