So, the expression and activity of furin as a proprotein convertase is necessary for processing of the enzymes, which stimulate tumor progression and metastasis.163 In summary, furin plays a significant role in tumor progression, invasiveness, and metastasis, so cancer cells frequently overexpress this protein.164–168 This furin overexpression most likely contributes to MV oncospecificity. This evidence concerns the gene FURIN and neoplasm.