The TPX2–Aurora A interaction is required for chromatin/kinetochore-mediated microtubule nucleation. U2OS, mTPX2^WT, mTPX2^AAA, and mTPX2^ΔN cells transfected with TPX2 or CON siRNA were treated on ice to completely depolymerize microtubules, transferred to 37°C for 90 s to allow repolymerization, and immediately fixed. Immunofluorescence images are shown of cells stained with α-tubulin and CREST (top rows) and Cep135 and DNA (bottom rows). In addition to aster microtubule polymerization associated with centrosomes, microtubule polymerization broadly associated with chromatin and often specifically associated with kinetochores was evident in all cell lines after CON siRNA and in mTPX2^WT cells after TPX2 RNAi. In U2OS, mTPX2^AAA, and mTPX2^ΔN cells after TPX2 RNAi, microtubule repolymerization was no longer seen associated with chromatin or kinetochores, but centrosome-associated microtubule aster polymerization was still evident. Bar, 10 μm.