IL6 and growth hormone-producing pituitary gland neoplasm: Marques et al. conducted a study on GH3 cells (extracted from 5 cases of human somatotropinomas) and proved that TAFs (tumor associated fibroblast) are able to secrete the CCL2, CCL11, CCL22, VEGF-A, IL-6, IL-8 and FGF-2 [69].