Figure 5. ALK1 Signaling through SMAD and HEY Prevents Tip Cell Specification.
HUVECs transfected with siRNA were labeled with green or red fluorescent dyes, mixed, coated on microcarrier beads, and embedded in fibrin. (A, B, D, and E) Representative images of sprouts 4 days after siRNA transfection. Scale bar, 65 μm.
(C) Quantification of percentage of target siRNA-transfected cells at the tip position of sprouts. Sprouts on 25–30 beads were quantified per experiment. Graphs represent the average of three to four experiments. All values are mean ± SEM. *p < 0.05; Student's t test.