STAT5b knockdown negatively affects directionality during wound closure. Wounds were made in confluent monolayers of siRNA-transfected BT-549 cells, and time-lapse microscopy was used to track cell movement into the wound over a 6-hour period. (a) Progressive line images tracking single cell nuclei of cells along the wound edge. Two independent experiments are shown. (b) Migration rate (μm/h) was calculated by dividing the length of the migration path by the total movie time. (c) Directional persistence (D/T) was determined as the net displacement (D) divided by the total length of the migration path (T). (b, c) Values from at least four independent experiments were used for calculations (siLuc, n = 24; siSTAT5b, n = 32). Student's t test was used to determine statistical significance (p < 0.05) between siLuc and siSTAT5b (*). Comparisons of migration rate were not statistically significant.