Impaired 3-dimensional functions on Matrigel and collagen. (A) MLECs were seeded on Matrigel and photographed at indicated times (bar = 1 mm). Total length of cellular cables was quantitated after 24 hours (*P < .001). (B) Representative photographs of Matrigel contraction data are shown for WT and Cd151-null MLECs (bar = 5 mm). Percent contraction (after 18 hours) is the average gel diameter/well diameter × 100 (*P < .05). Data are representative of 3 independent experiments with similar results. (C) MLECs were incubated within collagen gel for 48 hours, then fixed, stained with toluidine blue, and photographed (bar = 1 mm). Total tube length is quantitated (n = 2; *P < .05). (D) Representative images are shown of capillary-like structures sprouting from MLEC spheroids after 48 hours (bar = 100 μm). Total sprouting length is quantitated (*P < .005). Data are representative of 3 independent experiments with similar results. Note that the initial size of spheroids, when first transferred to collagen gel, was similar for WT and Cd151-null cells (136 ± 12 μm and 145 ± 13 μm, respectively).