The nuclear mitotic apparatus protein (NuMA) is a critical component of the mitotic spindle that is responsible for organizing minus-ends of microtubules at spindle poles. NUMA is regulated by phosphorylation and associates with dynein and dynactin in its phosphorylated form. Dephosphorylation of NUMA in anaphase results in the release from dynein and dynactin to allow spindle disassembly. NUMA, in association with dynein and dynactin, also interacts with 4.1R in a complex of spindle pole organizing proteins. Other NUMA interacting proteins include GAS41, tankyrase, and Rae1. These interactions indicate a broader role for NUMA function in the nucleus.