VEGFA and endometriosis: VEGF is regulated by multiple signaling pathways, with IL-1β playing a significant role.637 Normal endometrial stromal cells express VEGF at baseline, but its levels rise in response to estrogen and progesterone.637,638 Patients with endometriosis exhibit increased VEGF concentrations in peritoneal fluid and ectopic lesions, fostering a pro-angiogenic environment.639,640 VEGFR1/VEGF signaling in macrophages and fibroblasts further promotes lesion growth and lymphangiogenesis.641,642