Fig. 4.

Basal Runx1 expression is a prerequisite for HOXB4 mediated development of Runx1^hi/CD41^hi hematopoietic suspension cells. A Venus(Runx1^neg) and Venus (Runx1^int) cells were purified from dissociated day 6 EBs derived from HOXB4^const and HOXB4^ERT transduced Venus(Runx1) ESCs (upper row, mid-panel, ‘all’) by flow cytometry-based cell sorting (a representative post-sort re-analysis is shown: upper row, left panel, ‘Runx1^neg’ and right panel, ‘Runx1^int’) and placed on OP9 cells. B After sorting, 100 nmol/l (Tam were added to the cells expressing inducible HOXB4^ERT. After 5 days of co-culture on OP9 cells, CD41 and Venus(Runx1) expression were analyzed again. CD41^hi cells were only obtained when HOXB4 was expressed or induced in the Runx1^int cells. Non-sorted mass-cultures (mid-panels), sorted populations (left and right panels). C Correlation of HOXB4 expression levels with Runx1 expression.