A subset of genes is dysregulated in most murine APL samples. Expression profiles from GeneChip analyses designed to identify genes that were dysregulated in APL leukemic cells when compared with G-CSF–differentiated normal myeloid cells. APL expression was compared with 3 time points in the differentiation assay to capture the least and most differentiated myeloid cells (day 0, day 7) and the time point most enriched for promyelocytes (day 2). See “Materials and methods” for the algorithms used for each analysis (sets A-D). Heat maps show gene expression as a ratio of each sample to the reference sample in a continuous color range (green to red) of 0 to 1 (A, day 0; B, day 7; C, day 2; D, average of 6 APL samples). The same differentiation experiment (from set 1) is shown in each heat map. (A) Nineteen genes were highly expressed on day 0 and in APL cells, and had much lower expression on days 1 to 7 (set A). (B) Twenty-nine genes were highly expressed on day 7 and in APL cells, and had much lower expression on days 0 to 6 (set B). (C) Thirty-six genes were maximally expressed on day 2, had much lower expression on the other days, and in APL had less than 0.2 times the expression on day 2 (set C). (D) Thirty-two genes were highly expressed in APL cells and had much lower expression on day 2 (set D).