CD155 regulates cellular morphology. HT1080 cells were transfected with siRNA targeting CD155 or with a scrambled control duplex and plated on matrigel after 48 h. Cells were fixed and immunostained for CD155 expression before images were acquired for morphometric analysis. (a) Schematic showing measurement parameters. (b) Chang plot showing cell perimeter measurements. Perimeters values are expressed as percent of the average control perimeter. As a population, CD155 knockdown cells (dark circles) exhibited a significant increase in perimeter compared to controls (light circles). (c) Chang plot showing cell shape measurements. Cell shape was defined using the equation (4 × cell area) / cell perimeter2, where 1 indicates a perfect circle and smaller values indicate a more irregular shape. CD155 knockdown cells (dark circles) were more irregular in shape than scrambled controls (light circles). Perimeter: Δ avg = +18%; shape: Δ avg = -13%;p < 0.001, t-test; n = 120 scramble siRNA and 112 CD155 siRNA.