Sequential phenotypic analysis of differentiated hES cells in OP9 coculture. Representative phenotype of undifferentiated (day 0) and differentiated H1 hES cells on day 6 and day 9 of OP9 coculture. Single cell suspension from hES cell/OP9 coculture obtained at the indicated time was labeled with CD34 (y-axis) and with CD31, KDR, CD43, CD41a, or CD45 mAbs as indicated in right side of each row (x-axis). Numbers indicate percentages of positive cells and MFI (x-scale) in corresponding quadrants.