Alterations in gene expression mediated by either PML/RARα or PLZF/RARα in U937 cells. Pair-wise comparisons were performed to examine the gene effect; data from U937 cells were compared with that from either U937PR9 (for PML/RARα effect) or U937B412 (for PLZF/RARα effect) cells. Triplicate experiments were performed in a paired fashion at 3 different times. (A) Venn diagram of genes that are either (i) up-regulated or (ii) down-regulated by conditional expression of APL fusion proteins in each of 3 independent experiments. The criteria for altered gene expression include a 2-fold or more change in the raw value and a raw expression value of at least 1000 in the experimental group. (B) Northern blot confirmation of microarray data concerning genes that are commonly up- or down-regulated by induced expression of either PML/RARα or PLZF/RARα fusion protein. The same samples of total RNA used in the microarray analysis were used (10 μg/lane) in the Northern blot analysis. Each blot was rehybridized for GAPDH to ensure equal loading of RNA.