FIGURE 10. c-Met Ca²⁺ signaling within the nucleus.

Stimulation with HGF induces c-Met to translocate to the nucleus, and this depends upon importin β and the adaptor protein Gab1. In the nucleus, activated c-Met forms InsP₃ (although the topology of c-Met in the nucleus, and whether HGF remains bound to nuclear c-Met, are unknown). This acts on nuclear InsP₃ receptors to increase free nucleoplasmic Ca²⁺. In contrast, vasopressin induces the V_1a receptor to form InsP₃ in the region of the plasma membrane, which acts on InsP₃ receptors in the endoplasmic reticulum to increase free Ca²⁺ in the cytoplasm.