After the initiation of DNA condensation in prophase of mitosis, NuMA (NUMA1) is phosphorylated on threonine residue 2055 by the complex of Cdc2 (CDK1) kinase and Cyclin B1 (CCNB1). After the nuclear envelope breakdown, phosphorylated NuMA rapidly moves to the centrosomal region (Compton and Luo 1995, Hsu and Yeh 1996, Kotak et al. 2013). Another phosphorylation event occurs when NuMA associates with the mitotic spindle (Gaglio et al. 1995; Hsu and Yeh 1996). While CCNB1:p-T160-CDK1-dependent phosphorylation appears to plays an essential role in the targeting of NuMA to the spindle apparatus (Compton and Luo 1995, Hsu and Yeh 1996, Kotak et al. 2013), there may be additional protein kinases that promote the release of NuMA from the nuclear compartment at nuclear envelope breakdown (Saredi et al. 1997).