Several theories to explain the failure of Eg5 and CENPE inhibitors to date have been proposed, including mitosis-specific expression of the targets combined with low mitotic indices in solid tumours, mitotic slippage to evade cell death, suboptimal pharmacodynamic and pharmacokinetic profiles, resistance conferred by mutations in the targeted kinesins or CIN-induced, and compensation by functionally redundant kinesins such as KIF15 in the case of Eg5 inhibition [113,251,252]. This evidence concerns the gene KIF15 and cervical squamous intraepithelial neoplasia.