Ang1 drives CD41⁺ cells to ECs rather than HSCs. Expression pattern and differentiation potential of CD41⁺ cells derived from Flk-1⁺ MPCs were characterized. (A) Representative FACS analyses showing surface expression patterns of CD144, CD31, Tie2, Sca-1, and c-Kit, each compared with CD41 on Flk-1⁺ MPC–derived cells on day 1.5. (B) Images showing CD144⁺/CD41⁺ cells in endothelial colonies on day 1.5. Nuclei were stained with Hoechst. Scale bar represents 20 μm. (C) Experimental scheme for the differentiation potential of CD41⁺ cells. Sorted CD41⁺ cells on day 1.5 were replated on the freshly prepared OP9 cells, treated with Control, Ang1, sT2, or Ang1 + sT2 on days 1.5, and 3.5, and analyses were performed on day 6. (D,F) Representative FACS analyses of the populations of CD31⁺/CD144⁺ ECs and CD45⁺ HSCs from the sorted CD41⁺ cells. Numbers indicate percentages of each population. (E,G) Comparison of percentages of CD31⁺/CD144⁺ ECs and CD45⁺ HSCs from the sorted CD41⁺ cells (n = 3). *P < .05 compared with control; ^#P < .05 compared with Ang1.