Fig. 1.

Three variants of long-distance intercellular communication via signaling filopodia. Stable connections are formed between signaling cell (light gray cells on the left) and target cell (dark gray cells on the right). a The ligand secreting cell locates the ligand directly at the target cell and retracts the filopodium after ligand delivery. b The receptor-bearing target cell extends long signaling filopodia to the ligand secreting target cell. c Both, the ligand secreting and the receptor-bearing target cell extend signaling protrusions to contact