Breast cancers and breast cancer cell lines overexpress several mitotic regulators, including kinases that regulate the SAC such as Nek2, Mad1L1, Mad2L1, Mad2L2, BubR1, BubR1B, Bub3, Cdc20, and Mps1/TTK [32–34]. The gene discussed is MAD1L1; the disease is breast carcinoma.