In patients with MTC-related MEN2, the analysis of angiogenic factors found that patients with hereditary form display increased expression of VEGFR-1, whereas higher expression of MVD was observed in sporadic MTC [26].The VEGF-A and its receptors mRNA levels were evaluated in a large cohort of PHEO (102 patients with sporadic PHEO and 86 with hereditary form); the samples were separated into two groups depending on the presence of activation of the pseudo-hypoxic pathway. This evidence concerns the gene FLT1 and medullary thyroid gland carcinoma.