Before revision:  To distinguish between  chemotactic approach and blind migration, we present an objective method that is based on the analysis of time-lapse recorded cell migration trajectories : For each movement of a cell relative to the position of potential targets, we compute a p-value that quantifies how likely the direction of this movement step is under the null-hypothesis of blind migration. The resulting distribution of p-values, pooled over all recorded cell trajectories, is then compared to an ensemble of reference distributions in which the positions of targets are randomized. We validate our method with simulated data and demonstrate that the method reliably detects the presence or absence of long-range cell-cell interactions.
After revision:  To distinguish between chemotactic approach and blind migration, we present an objective method that is based on the analysis of time-lapse recorded cell migration trajectories . First, we validate our method with simulated data and demonstrate that the method reliably detects the presence or absence of long-range cell-cell interactions.