FLT1 and neoplasm: They bind with their corresponding tyrosine kinase receptors (VEGFR-1, VEGFR-2, and VEGFR-3), activating a downstream signal, such as (PI3K), serin/trionine protein kinase alpha (Akt), and mitogen-activated protein kinase (MAPK), eliciting the development of angiogenesis and increasing vascular permeability, and the growth of lymphatic vessels that drain extravasated fluid, proteins, and tumor cells (lymphangiogenesis) [45].