Based on the fact that TNF-α and TNFR1 are present in normal and tumoral anterior pituitary cells [26,27], we hypothesized that TNF-α may enhance MMP-9 and VEGF expression, which, in turn, contributes to hemorrhagic transformation in pituitary adenomas via degrading components of vascular basement lamina and increasing vascular permeability. Here, TNF is linked to pituitary gland adenoma.