Lower levels of PU.1 expression in APL patients as compared to non-APL AML patients. (A) Four representative gene expression profiling data sets were retrieved, including GSE1729, StJude, GSE10358 and GSE1159. White boxes indicate the expression levels of PU.1 in APL patients, and gray boxes represent the levels of PU.1 in non-APL (other AML subtypes) patients. The differences between the two groups were assessed using the two-tailed t test. The p-values are shown in the panels. (B) The inverse correlation between PML-RARα and PU.1 mRNA expression was assessed by quantitative real-time RT-PCR using 10 fresh APL patient samples (Table 1). The correlation coefficient for PML-RARα versus PU.1 was r = −0.325. Each symbol represents the average values from individual patients.