PLK1 and breast cancer: The fact that multiple different tumorigenic behaviors were affected by perturbing CEP55 expression suggests that, like other mitotic proteins [e.g., Aurora‐A (Fu et al, 2007), Eg5 (Yu & Feng, 2010), PLK1 (Ito et al, 2004; Weichert et al, 2005), NEK2 (Zhong et al, 2014)], it could regulate multiple aspects of breast cancer development.