The TPX2–Aurora A interaction is required for cold-stable microtubule stability and organization in prometaphase. mTPX2^WT, mTPX2^AAA, and mTPX2^ΔN cells were transfected with TPX2 or CON siRNA. 48 h after transfection, cells were treated on ice for 5 min and fixed. Fluorescence images are shown of cells stained with anti–α-tubulin (microtubules) and DAPI (DNA) showing cold-stable microtubule populations. Bar, 10 μm.