However, SFRP2 and 4 (secreted-frizzled related protein), Wnt antagonists, considered as tumor suppressor genes, were downregulated in pituitary adenomas, in particular in invasive tumors, suggesting a role of the Wnt pathway in the progression of PitNETs [50,51,52]. The gene discussed is SFRP2; the disease is pituitary gland adenoma.