To better understand the lack of efficacy of the SSTR2 somatostatin analogs in NFPA, we evaluated the mRNA expression levels of ZAC1 and SSTR subtypes 1, 2, 3 and 5 in NFPA and compared them to those of somatotropinomas and normal pituitaries. This evidence concerns the gene SSTR2 and non-functioning pituitary adenoma.