To test the capacity of In1-ghrelin peptides to induce functional responses in pituitary tumor cells, we measured the kinetics of free cytosolic calcium concentration ([Ca2+]i) in single cells derived from GH-omas, ACTH-omas, NFPAs and PRL-omas, as well as the levels of phosphorylation of two signaling pathways (MAPK and Akt; p-ERK1/2 or p-Akt, respectively) in GH-omas in response to treatment with acylated In1-ghrelin peptides as compared with that of AG. This evidence concerns the gene MAPK3 and pituitary tumor.