Figure 1.

Main signaling pathways and molecular effectors implicated in the regulation of individual phases of the cytolytic process. The sequence of steps leading to the activation of cytolytic machinery are represented as: lytic synapse formation (A), secretory apparatus polarization (B), lytic granule secretion (C), and lytic granule trafficking and retrieval (D). The continuous line arrows indicate the signaling pathway likely common to NK cells and CTLs. Large-dashed arrows indicate the exclusive pathways of NK cells, while fine-dashed arrows indicate the exclusive pathways of CTLs.