Correlation between CYP26A1 transcriptional activity and the in vitro blasts sensitivity to ATRA. Heterogeneity in the in vitro differentiation rates of 7 populations of APL blasts displaying varying sensitivities to ATRA. (A) Results of the NBt test performed at days 3 and 6. Error bars represent the standard error (n = 2). (B) Positive correlation between blasts sensitivity at day 3 and the transcriptional level of CYP26A1 and HOXA10v2. Transcriptional modulation (Log₁₀) was calculated between ATRA-treated and untreated blasts.