MAD1L1 is a component of the mitotic spindle-assembly checkpoint that prevents the onset of anaphase until all chromosome are properly aligned at the metaphase plate. MAD1L1 functions as a homodimer and interacts with MAD2L1. MAD1L1 may play a role in cell cycle control and tumor suppression. Some studies indicate associations of MAD1L1 with psychiatric disorders, including schizophrenia, bipolar disorder, and depression.  Three transcript variants encoding the same protein have been found for this gene.