Regulates PLK1 kinase activity at kinetochores and promotes faithful chromosome segregation in prometaphase by bridging kinase and phosphatase activities (PubMed:34260926). Phosphorylation of FIRRM by PLK1 negatively regulates its interaction with the phosphatase, PPP1CC, thus creating a negative feedback loop for maintaining proper PLK1 kinase activity during mitosis (PubMed:34260926). In complex with FIGL1 may regulate homologous recombination (PubMed:29608566).
