Figure 3.

Cyclin E1 overexpression causes chromosome segregation errors and aneu-ploidy in MEFs. (A) Chromosome counts on metaphase spreads of the indicated MEFs. (B) Chromosome segregation analysis of MEFs expressing H2B-mRFP. Images: Ccne1^T MEFs with indicated segregation errors. (C) Incidence of pseudobipolar or multipolar spindles in metaphases stained for αTubulin and γTubulin. Image: Ccne1^T MEF with indicated spindle defect. (D) Representative metaphases with perpendicular (top) and non-perpendicular spindles (bottom). (E) Incidence of non-perpendicular metaphase spindles. (F) Representative images of G₂ MEFs with normal (top) and premature (bottom) centrosome disjunction. (G) Measurements of centrosome separation in G₂ MEFs staged for equal pHH3 expression. (H) Representative images of pPlk1-stained prophases grown with and without dox. (I) Quantification of pPlk1 levels at centrosomes (normalized to γTubulin levels). (J, K) As in H for cyclin B2 and pAurA, respectively. (L, M) Western blots of mitotic shake-off lysates probed for the indicated proteins. Data in A-C, E, G, I-K represents mean ± s.e.m. Statistics: A-B, E, G, I-K, two-tailed paired t-test. C, two-tailed unpaired t-test *P < 0.05, **P < 0.01. Scale bars, 5 μm.