Cyclin B1 overexpression and proteasome inhibition fails to induce premature mitosis in Cdh1-ablated cells.

<p>(A) Western blots for Cdh1, cyclin B1 (CycB), and tubulin, of lysates from cells transfected with GL2 or Cdh1 siRNAs, followed by transfection with cyclin B1-YFP (CycB1-YFP) and/or treatment with proteasome inhibitor MG132. One asterisk indicates endogenous CycB, two asterisks indicates ectoptic CycB1-YFP. (B) Cell cycle distribution of GL2 and Cdh1 siRNA-transfected cells from (A) as determined by PI staining followed by flow cytometry. (C) Fifty thousand GL2-siRNA-transfected cells (top) and Cdh1-siRNA-transfected cells (bottom), either untreated or treated with MG132 and/or transfected with CycB1-YFP, on pseudo-color scatter plots of PI (abscissa) and pHH3 content (ordinate). High DNA and high pHH3 (M phase) gates (blue “M”) and low DNA and high pHH3 (abnormal G1/S cells) gates (green “G1/S”) are shown with their respective cell frequencies.