在哺乳动物体内有两型肿瘤坏死因子α(TNFα)共同存在,一种是以细胞膜结合分子的形式表达于细胞表面的跨膜型TNFα(tmTNFα),另一种是广泛分布的可溶性TNFα(sTNFα)。tmTNFα作为sTNFα的前体,在适当的条件下被金属蛋白酶切割而释放至体液中形成sTNFα。研究发现tmTNFα虽然是 In mammals there are two types of tumor necrosis factor alpha (TNFα) co-exist, one is in the form of membrane-bound molecules expressed on the cell surface transmembrane TNFα (tmTNFα), the other is a widely distributed soluble TNFα (sTNFα ). As a precursor of sTNFα, tmTNFα is cleaved by metalloproteinase under appropriate conditions and released into bodily fluid to form sTNFα. The study found that although tmTNFα is