Knockdown of RASIP1 affects EC-EC attachment. (A) Differential interference contrast images of control and RASIP1 shRNA-treated HUVECs in an angiogenic sprouting assay, 24 and 48 hours after seeding. Most sprouts have moved into the fibrin matrix yet remain attached to ECs on the bead in the control group (left), whereas a subset of sprouts detached from the beads in the RASIP1 knockdown group (arrowheads, right). Scale bars, 100 μm. (B) Quantification of detached sprouts in 3 angiogenic sprouting experiments 24 and 48 hours postseeding. Twenty beads were counted per experiment. Error bars are interexperimental SEM. *P < .002 (2-way ANOVA). (C) Quantification of HUVEC migration rate (control and RASIP1 shRNA) in a scratch wound assay. (D) Quantification of the number of detached HUVECs from the leading edge in the scratch assay; 21 to 23 movies were scored per condition. (E) Relative measurement of 40-kDa FITC-dextran fluorescent signal passed across a control or RASIP1 shRNA-treated HUVEC monolayer. *P < .05 (Student t test). Error bars indicate SD for panels C-E.