AtMAP65-1 plays a role in stabilizing anti-parallel microtubules in the central spindle at anaphase to early cytokinesis but is not essential at the midline of the phragmoplast at later stages. The timing with which the MAP65-1 was targeted to the spindle appears to be regulated by a phosphorylation sensitive switch. AtMAP65-1 enhances microtubule polymerization and promotes nucleation and stabilizes microtubules against cold treatment and dilution. The Arabidopsis contains nine MAP65 proteins
