sentences:  Migration is caused by a bi-directional signaling mechanism in which the engagement of the ephrin ligand with the EphB receptor regulates the actin cytoskeleton dynamics to cause a "repulsion".Cells remain in place once the interaction ceases to a stop.While the mucus secreting Goblet cells and the absorptive cells move towards the lumen, mature Paneth cells move in the opposite direction, to the bottom of the crypt, where they reside.