SMAD3（SMAD family member 3），癌症关联基因，基因ID：4088，由该基因编码的蛋白质属于smad，一个类似于果蝇基因‘母亲抗十五瘫’（mad）和秀丽隐杆线虫基因sma的基因产物的蛋白质家族。smad蛋白是介导多种信号通路的信号转导和转录调节因子。这种蛋白作为一种转录调节剂，被转化生长因子β激活，并被认为在致癌过程中发挥调节作用。[由RefSeq提供，2009年4月]The protein encoded by this gene belongs to the SMAD， a family of proteins similar to the gene products of the Drosophila gene 'mothers against decapentaplegic' (Mad) and the C. elegans gene Sma. SMAD proteins are signal transducers and transcriptional modulators that mediate multiple signaling pathways. This protein functions as a transcriptional modulator activated by transforming growth factor-beta and is thought to play a role in the regulation of carcinogenesis. [provided by RefSeq， Apr 2009]。