Accumulation of ubiquitinated MDM2 following PN treatment requires the PIKK ATM. A, Western blots of nuclear extract proteins from ZR-75-1 cells treated with 15 μmol/L PN and 1 μmol/L or 20 μmol/L wortmannin (Wort) for 3 h as indicated. Accumulation of ubiquitinated MDM2 following PN treatment requires the PIKK ATM. A, Western blots of nuclear extract proteins from ZR-75-1 cells treated with 15 μmol/L PN and 1 μmol/L or 20 μmol/L wortmannin (Wort) for 3 h as indicated. B, Western blots of nuclear extract proteins from cells possessing (AT22IJE-TpEBS7-YZ5, left) or lacking (AT22IJE, right) ATM treated with 15 μmol/L PN. C, Western blots of nuclear extract proteins from ZR-75-1 cells treated with ATM siRNA for 72 h and 15 μmol/L PN for the final 3 h, as indicated. D, Western blots of whole-cell extract proteins from ZR-75-1 cells treated with control RISC-free siRNA (left) or HDAC siRNA (right) for 72 h and 15 μmol/L PN for the final durations indicated. E, p21 (top) and PUMA (bottom) mRNA levels in ZR-75-1 cells treated with control RISC-free siRNA (white columns) or HDAC siRNA (gray columns) for 72 h and 15 μmol/L PN for the final durations indicated, as determined using a real-time qRT-PCR assay after normalization against glyceraldehyde-3-phosphate dehydrogenase mRNA levels. Y.N. Vashisht Gopal et al. Mol Cancer Ther 2009;8:552-562 ©2009 by American Association for Cancer Research