Figure 4. Pituitary senescence progression model.

Pituitary tumor pathogenesis has an initial proliferative phase involving IL-6 secreted from the FS cells, which induces proliferation of the pituitary tumor cells. It is followed by a phase of stopping proliferation in which senescence mediated by the autocrine IL-6 produced by the tumor cells themselves, might contribute to establish a benign tumor with stable growth arrest.