The nuclear envelope breakdown (NEBD) happens in late prophase of mitosis and involves disassembly of the nuclear pore complex, depolymerization of the nuclear lamina, and clearance of nuclear envelope from chromatin. NEBD allows mitotic spindle microtubules to access condensed chromosomes at kinetochores and enables nuclear division and segregation of genetic material to two daughter cells. For a recent review, please refer to Guttinger et al. 2009.
In mitotic prophase, chromatin detaches from the nuclear envelope, and this contributes to the nuclear envelope breakdown. VRK1 (and possibly VRK2) mediated phosphorylation of BANF1 (BAF), a protein that simultaneously interacts with DNA, LEM-domain inner nuclear membrane proteins, and lamins (Zheng et al. 2000, Shumaker et al. 2001, Haraguchi et al. 2001, Mansharamani and Wilson 2005, Brachner et al. 2005) is considered to be one of the key steps in the detachment of the nuclear envelope from chromatin (Bengtsson and Wilson 2006, Nichols et al. 2006, Gorjanacz et al. 2007).