Myc up-regulates the expression of Aurka and Aurkb. (A) Quantitative SYBR Green real-time PCR analysis (quantitative RT-PCR) of Aurka and Aurkb transcript levels in bone marrow (BM) and splenic (spleen) B220⁺ B cells from 4-week-old wild-type (wt; white bars) or Eμ-Myc (black bars) littermate mice. Levels of mRNA are standardized to the expression of Ubiquitin (Ub). Bars represent the mean of 3 experiments ± SEM. *P < .05. (B) Immunoblot analysis of the indicated proteins in splenic B220⁺ B cells from 4-week-old wild-type (wt) or Eμ-Myc-transgenic littermate mice. (C) Quantitative RT-PCR analysis of c-Myc, Aurka, and Aurkb RNA expression in P493-6 human B cells that bear a tetracycline-regulated Myc gene. The cells were treated with tetracycline for the indicated time (+Tet), washed, and cultured in tetracycline-free medium (−Tet). Levels of mRNAs were standardized to the expression of Ubiquitin (Ub), which is not regulated by Myc. (D) Top panel: Immunoblot analysis of the indicated proteins from the same P493-6 cells as in panel C. The numbers below the immunoblots indicate the percentage of cells in S phase (PI staining) assessed by flow cytometry. Tet indicates tetracycline.