NRP1 and neoplasm: TGF-β is a secreted cytokine that is concerned with body homeostasis, tissue repair, inflammation, and immune responses,211 which is also involved in cell growth, differentiation, proliferation, autophagy, apoptosis, and tumor angiogenesis.212 There are three types of single-pass transmembrane receptors specifically interact with TGF-β, named type I (TβRI), type II (TβRII) and type III (TβRIII).