Mitotic arrest deficient 2-like protein 1 (MAD2L1) is also known as Mitotic spindle assembly checkpoint protein MAD2A (HsMAD2), MAD2. MAD2L1 / MAD2 belongs to the MAD2 family. MAD2L1 / MAD2 contains one HORMA domain. MAD2L1 is the component of the spindle-assembly checkpoint that prevents the onset of anaphase until all chromosomes are properly aligned at the metaphase plate. MAD2L1 / MAD2 is required for the execution of the mitotic checkpoint which monitors the process of kinetochore-spindle attachment and inhibits the activity of the anaphase promoting complex by sequestering CDC20 until all chromosomes are aligned at the metaphase plate.