Glycodelin A, a promoter of neovascularization and cell proliferation, was examined in follicular phase serum of adolescent girls with endometriosis (n = 33) aged 13–19 alongside TNF-α and IL-6, but none of these proteins showed a different expression compared with adolescents without endometriosis (n = 17) [46]. Here, IL6 is linked to endometriosis.