Megakaryocyte markers are inhibited during EB differentiation on OP9 cells after EKLF induction. (A) CD41 and CD42d expression was monitored by FACS in day 6 EBs or at 24 (Mkd7), 48 (Mkd8), or 72 hours (Mkd9) after placement on OP9 cells with thrombopoietin (TPO) with or without doxycycline. (B) All gates were drawn based on negative controls for each sample (not shown). Numbers within the FACS indicate the percentage of CD42d⁺ cells in each population. Data in panel A are presented as the ratio of induced to uninduced CD42d⁺ levels from 7 independent experiments after subtracting negative controls for each sample using the Overton cumulative histogram subtraction algorithm⁴⁸  (thus the pretreated EBd6 ratio is one). Error bars are SD.