Supplementary Figure Legends 1-6, Movie Legends 1-2

Supplementary Figure 1. Tacc3 expression in tumors developed in p53-deficient mice. Indicated tumors were isolated and sections were stained with HE (HE). Immunohistochemistry of indicated proteins was performed. Bar=200µm.

Supplementary Figure 2. Expression of Tacc3 protein in thymic lymphoma. Lymphoma tissues of indicated mice were isolated and stained for Tacc3. Bar=100µm.

Supplementary Figure 3. Tacc3 deletion does not induce abnormalities in normal thymi of p53-deficient mice. a, Tacc3S/W and Tacc3S/D mice were treated with 4OHT five times in seven days and thymi were analyzed by HE staining (top) and Immunohistochemistry of Tacc3 (bottom). Bar=200µm. b, Immunofluorescense analysis of TUNEL (green in top panels) and PCNA (green in middle panels). Images of PCNA and magnifications were shown in the bottom. Tacc3 was shown in red. Cell nuclei were stained with DAPI (blue). Bar=50µm, Bar in inset=25µm. c, Immunohistochemistry of senescence markers. Bar=100µm.

Supplementary Figure 4. Tacc3 disruption in adult tissues does not induce apoptosis. Indicated tissues from p53+/+; Tacc3S/W; CreERT2 (Tacc3S/W) or p53+/+; Tacc3S/D; CreERT2 (Tacc3S/D) mice treated with 4OHT five times in 7 days. HE staining of each tissue was shown in left (HE). Immunofluorescence analyses of TUNEL assay (green) and Tacc3 (red) were shown in right. Cell nuclei were stained with DAPI (blue). Bar in HE staining=100µm, Bar in immunoflourescence=50µm.

Supplementary Figure 5. Tacc3 is localized at mitotic spindles and centrosomes in thymic lymphoma cells. Immunofluorescence analysis of endogenous Tacc3 protein (red), -tubulin (green), and DNA (blue) during different phases of mitosis. a. G1 phase, b. G2 phase, c. prometaphase, d. metaphase, e. anaphase, f. telophase. Images of Tacc3 in merged pictures are shown at the left. Bar=10 µm.

Supplementary Figure 6. Jurkat cells contain supernumerary centrosomes. a, Jurkat cells were infected with lentivirus expressing control shRNA (control) or Tacc3 shRNA (sh1) and stained with a-tubulin (green) and g-tubulin (red in top panels) or pericentrin (red in bottom panels) after 48 hours after infection. Images of g-tubulin and pericentrin in merged pictures were shown in right. bar=10µm. b, Cells were treated as described in (a), and stained with a-tubulin (green) and centrin 2 (red). Images of centrin2 in merged pictures and their magnifications were shown in right. Bar=10µm.

Supplementary Video 1. Mitosis of control mouse lymhoma cells. Movie of H2B-GFP fluorescence image of thymic lymphoma cells generated from p53-/-; Tacc3S/D; CreERT2 mouse without 4OHT treatment described in Figure 4g is shown.

Supplementary Video 2. Mitosis of Tacc3 depleted mouse lymhoma cells. Thymic lymphoma cells generated from p53-/-; Tacc3S/D; CreERT2 mouse were treated with 4OHT and movie of H2B-GFP fluorescence image described in Figure 4g is shown.