Tumor-mass sequencing data indicate that the genes that are frequently mutated in colon cancer function to prevent CIN, suggesting that progressive CIN is an integrated process in colonic carcinogenesis.3 Most primary lung cancers carry loss of heterozygosity, which is associated with CIN, further implicating CIN in lung carcinogenesis.12 CIN can be caused by mutations in various genes, many of which are bona fide mitotic regulators, such as mitotic spindle checkpoint components BubR1 and Mad2, the mitotic motor Cenpe, and chromosome cohesion regulators such as Sgo1. This evidence concerns the gene BUB1B and cervical squamous intraepithelial neoplasia.