Before revision:  We then apply the method to data from experiments with highly migratory human-derived natural killer (NK) cells and nearly stationary K562 tumor cells as targets that are dispersed in a 3-dimensional collagen matrix.
After revision:  We then apply the method to data from three-dimensional collagen gels, interspersed with highly migratory human-derived natural killer (NK) cells and nearly stationary K562 tumor cells as targets that are dispersed in a 3-dimensional collagen matrix.