Why does the nuclear membrane disappear during mitosis?

Question

Science question that I'm stuck on. Why does the nuclear membrane of a cell disappear during the prophase of mitosis?

Answer 1

Proteins called lamins underlie and stabilize the nuclear envelope/membrane. These proteins, when not phosphorylated, polymerize. During prophase, a cyclin-dependent kinase is activated that phosphorylates the lamins, causing them to depolymerize and the nuclear membrane to disassemble. At the end of mitosis, the lamins are dephosphorylated and re-polymerize, facilitating re-assembly of the nuclear membrane.

Answer 2

If it doesn't, then the cell can't divide. Sometimes the answer is really simple.