Nexin is a flexible crosslinker that converts sliding into bending movement. Active as dimer. Movement along microtubules is combination of binding and release plus rotation. Anterograde axonal transport Saltatory movement in cytoplasm. Prophase Condensation of chromosomes, breakdown of nuclear envelope, and breakdown of intermediate filaments triggered by phosphorylation - M phase specific kinase.
Mitotic spindle begins to form outside the intact nuclear envelope.
In anaphase, kinase is inactivated, so constitutive phosphatases cause dephosphorylation of nuclear lamins. Nuclear envelope re-forms, initially around chromosomes, but later fuses together to make complete nuclear membrane. In some fashion, histone dissociation drives chromatin condensation into the mitotic chromatids. Beacuse the nucleoli are formed from nucleolar organizer regions located on multiple chromosomes, they break down during prophase. Mitotic spindle formation.