Angiogenesis is essential for malignant tumor growth and metastasis because new vessels offer extra oxygen and nutrients and because endothelial cells in the neovasculature have high permeability.104 It was reported that signal transducer and activator of transcription 3 (STAT3) activation was capable of increasing miR-21 expression in exosomes released by CSE-transformed HBECs. This evidence concerns the gene STAT3 and neoplasm.